C3 frame differences 69,70-73

[Joseph H.]

OK, thought I would ask the experts again. I have read much here about C3 frames, understanding that a 68 frame is different from 69 because of the kickup braces and some differences in front gussets that the extensions bolt to. What about 69 thru 73? Are there any differences comparing these years for a 4 speed frame? Would for instance a 72 - 4 speed frame work without any mods on a 69?

Regards,
Joe

[Lynn H.]

Re: C3 frame differences 69,70-73

Joe,
The 72 manual transmission frame would be a direct replacement for a 69 frame. There were no significant differences until 73 when they changed the front bumper. There is an old restorer article by David E. Reisner, and Bill G. Grace that charts the differences in the frame each year from 1963 to 1980.
Lynn

[Jim B.]

Re: C3 frame differences 69,70-73

The mid to late 68's had basically the same frame as the 69. Kickups included. Larger changes came in 70 and up.

[Joseph H.]

Re: C3 frame differences 69,70-73

Thanks so far for the info. Let me rephrase a bit more. If I needed to replace a 69 4 speed frame, what years could I use without having to any make modifications to the replacement frame? This switch would include removing everything from the 69' rolling chassis and moving it to the replacement frame. I did not think I could use a 68' frame without making changes to it whether or not it was early or late. I read here in other threads because of the front gussets and some radiator support mount changes.

So, I am looking for a replacement frame and I know of a late 68 rolling chassis and a 72 rolling chassis, both 4 speeds.

Lynn, so there are some changes to the 73 also, I assume then just in the front because of the new bumper? Please expand upon. Also, I am just trying to understand the differences, like I know the 4 spd and A/T frames differ in the trans mount, but what exactly is the difference in the mount?

Anyone have the restorer article handy or could possibly post it for me?

Thanks

[Terry M.]

Re: C3 frame differences 69,70-73

Didn't rubber body mounts come in 1973? If so the body mounts on the frame are lower than earlier frames to accommodate the thickness of the rubber. Best to stick with the "aluminum cookie" body mounts.

[Jim T.]

Re: C3 frame differences 69,70-73

Thanks so far for the info. Let me rephrase a bit more. If I needed to replace a 69 4 speed frame, what years could I use without having to any make modifications to the replacement frame? This switch would include removing everything from the 69' rolling chassis and moving it to the replacement frame. I did not think I could use a 68' frame without making changes to it whether or not it was early or late. I read here in other threads because of the front gussets and some radiator support mount changes.

So, I am looking for a replacement frame and I know of a late 68 rolling chassis and a 72 rolling chassis, both 4 speeds.

Lynn, so there are some changes to the 73 also, I assume then just in the front because of the new bumper? Please expand upon. Also, I am just trying to understand the differences, like I know the 4 spd and A/T frames differ in the trans mount, but what exactly is the difference in the mount?

Anyone have the restorer article handy or could possibly post it for me?

Thanks

Joesph one difference between the 4-speed and automatic is the how the crossmember is attached. The 4-speed is welded to the frame rails and the automatic is easily removable, it is bolted to the the frame rails. I do not know if a 4-speed is a bolt in replacement with no modifications needed for say if I wanted to convert my 70's turbo 400 transmission to a 4-speed. Someone has the answer.

[Alan S.]

Re: C3 frame differences 69,70-73

Hi Joseph,
I looked through the 2 RESTORER Indexes and the up-dated one that Jeff Salz did but don't see the article. I'll look more carefully this evening and let you know if I can send it to you.
Perhaps someone will find it for you before then.
Regards,
Alan

[Lynn H.]

Re: C3 frame differences 69,70-73

I have the article and chart in front of me but it is in the NCRS Restoration and Maintenance Encyclopedia 63-67 Chassis Volume, and not the actual Restorer (although I have that also). The chart has VERY SMALL print and my old eyes have a hard time reading it as is, but if I cannot locate the volume number, I will attempt to scan and post. As far as the frame, I believe for an exact match you will need the 69-72 manual transmission frame (I do not have personal knowledge of the late 68 frame). For 73 in addition to the rubber mounting the front of the frame horn was shortened for the new extension, and the bolt pattern changed for the soft bumper extension for that year. I have personally modified a 73 frame to go under the 69 , and it requires very little modification, so I would say this frame WILL suit your needs, with very little work that WILL NOT be noticeable once assembled.
Lynn

[Lynn H.]

Re: C3 frame differences 69,70-73

Busy morning, I have not been able to find exactly which volume and issue of the Restorer this is in, but I have a photo of the frame chart that is readable on my desktop. Let's see how it shows up here. If anyone is having problems seeing or reading it, please send me a PM with your email and I will send a readable photo to you.
Lynn

[Joseph H.]

Re: C3 frame differences 69,70-73

Lynn,
Thanks I can print and read the chart. If someone can chime in on the differences between 68 and 69 I would appreciate it. Reading the chart (assuming I read it correctly) would lead me to believe that that only difference between a 68 to 69 frame are the kickup braces. I have read here that the front frame extensions are also different.
Anybody out the that actually has pics of the front frame horns from a 68 and 69 so I can see the differences.

Thanks,
Joe

[John C.]

Re: C3 frame differences 69,70-73

Joe

The front frame horns are different between a 68 and 69. In 68 the radiator core support attaches directly to the frame. In 69 it attaches to the front bolt on cross member. Also the brackets that bolt the front cross member to the frame have a different hole pattern in 68 and 69.

John

[Terry B.]

Re: C3 frame differences 69,70-73

Joe,

Mid 68 frames had the kick up gussets bracing but all '68 bodies had the ability to accept the extra bracing. I had to replace my '68 frame a few years back that had an automatic transmission and found a real nice 72 frame worked well. I had to drill 2 additional holes in the frame to have the front bracing work. I believe there is something from the NCRS Bookstore on frames that would help you. I would suggest you call Cincinnati and check.

[Wayne W.]

Re: C3 frame differences 69,70-73

Joe,

Mid 68 frames had the kick up gussets bracing but all '68 bodies had the ability to accept the extra bracing. I had to replace my '68 frame a few years back that had an automatic transmission and found a real nice 72 frame worked well. I had to drill 2 additional holes in the frame to have the front bracing work. I believe there is something from the NCRS Bookstore on frames that would help you. I would suggest you call Cincinnati and check.

It had to be a little more than that because the front mounting of the radiator support is different.

[Lynn H.]

Re: C3 frame differences 69,70-73

There is always more...
Joseph,
I think everyone will agree that you should be able to use anything from late 68 thru the 73 model year for your 69 with only minor mods, and it will work fine.
Lynn

[Terry B.]

Re: C3 frame differences 69,70-73

Wayne,

If you are referring to the radiator core support, its' main attachment is on each side of the body on a '68.

I did have to have welded a different style of the emergency cable brackets (2) on the '72 frame but I honestly cannot think of anything else besides the 2 additional holes previously mentioned for the '72 frame I used.

I agree with Lynn that later '68 through '72 for sure & perhaps '73 frames will work fine with little modification needed.