Correct rear differential cover for 63?

[Daniel T.]

I have everything apart in the rear end for rebuild on my 63 swc, I'm trying to figure out if it has the original or correct rear diff cover/spring mount.

I'm seeing a couple possible #'s, 3830303 (63-64) and 3871375 (seems to be the newer but I see it refereed to as 63-67 or later). 6th and 7th judging manuals, well either I was reading them wrong last night or they are referencing the # on the side of the differential not the rear cover? Sorry if this has been asked before but I tried searching and only came up with some questions on date codes. The car is a December 62 build if that matters. thanks Dan

[Timothy B.]

Re: Correct rear differential cover for 63?

Dan, 3830303 is the cover for 63-64 and maybe (not 100%) early 65.

[Peter H.]

Re: Correct rear differential cover for 63?

Hi Daniel. I Have Wondered For Years The Wording Of The Manual. Your Right They Are Referencing The Differential Carrier The Rear Cover/spring Support Is Definitely 3830303. Peter Hannigan 🇨🇦

[Daniel T.]

Re: Correct rear differential cover for 63?

thanks all... that's actually ok then; when I got the car it had a 66 dated sb center (marked for 3:70's) with 4:10's and posi; but it came with the 63 case/carrier and a bucket of parts which I'm having built up now with another donor ring/pinion/posi. I wanted to be sure and use the correct rear cover/spring support when everything goes back together.

[Mark M.]

Re: Correct rear differential cover for 63?

The 303 cover is correct for 63-64 and early 65. I have 2 early 65 3830303 covers here on rear ends with the later (as on all 3871375 covers) tapered course threaded drain plug which came on rear ends built Aug. 64 and Sept. 64. They also have the white plastic vent. The 63-64 covers have a fine thread drain plug and a short steel vent. Somewhere in early 65 or maybe very late 64, the plug and vent seems to have changed. One of these early 65's here have the metal posi tag as seen on 63-64 appose to the 65 red plastic tag change. My guess is GM was using up the 303 covers and tags before switching to the 375. The cover # is cast on top edge upside down as viewed from it's back on car and just the last 3 #'s are cast inside the cover. Covers had no date til possibly 67! Hope this helps and you have your original.

[Joe L.]

Re: Correct rear differential cover for 63?

I have everything apart in the rear end for rebuild on my 63 swc, I'm trying to figure out if it has the original or correct rear diff cover/spring mount.

I'm seeing a couple possible #'s, 3830303 (63-64) and 3871375 (seems to be the newer but I see it refereed to as 63-67 or later). 6th and 7th judging manuals, well either I was reading them wrong last night or they are referencing the # on the side of the differential not the rear cover? Sorry if this has been asked before but I tried searching and only came up with some questions on date codes. The car is a December 62 build if that matters. thanks Dan

Dan------

I agree with the other responders. And, you can be absolutely certain that your 1963 was never built with a 3871375 differential cover because that part number could not and did not exist in 1963. Period.