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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
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| | | | Joined: Aug 2011 Posts: 154 Shop Shark | | Shop Shark Joined: Aug 2011 Posts: 154 | My truck is a GMC 55.2 - but it was rebuilt and has a 350 and turbo 350 from a 78 blazer. My FIL built the truck and he recently passed away. I'm doing some work on the brakes and am trying to figure out if the rear end is from the 55.2 or the 78 blazer where he got the engine. Are there any tale-tale signs that would point me in either direction to tell me what year the rear end is? I can snap some photos tonight if it would help.
1955 GMC 100 Series 2
| | | | | Joined: Nov 2005 Posts: 6,100 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 6,100 | Hy GMTK, pictures are always very helpful. | | | | | Joined: Aug 2011 Posts: 154 Shop Shark | | Shop Shark Joined: Aug 2011 Posts: 154 |
1955 GMC 100 Series 2
| | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | Looks to me like a 1955 GMC 2nd Spicer 45.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | I don't know, Dave, looks more like a Truck 12 bolt to me. I've never seen a Spicer without a filler plug on the cover, and if I'm not mistaken, I believe that the 45 has a 10 bolt cover, same as the 44. One way to know for sure is to look for a "45" somewhere on the center section.
Bill Burmeister
| | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | If it were in my shop I could tell quickly be the brake drums.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | Ah, yes, the brake drums. Forgot about those, made of Unobtanium. Perhaps a pic of the drums with a wheel off, as well as one from the front of the diff housing might be in order.
Bill Burmeister
| | | | | Joined: Mar 2010 Posts: 10,279 Renaissance Man | | Renaissance Man Joined: Mar 2010 Posts: 10,279 | Looks like a 12 bolt with the funky shaped cover. I am basing this on the video taken from a sinking ship on rough seas, it appears.
Carl
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
| | | | | Joined: Aug 2011 Posts: 154 Shop Shark | | Shop Shark Joined: Aug 2011 Posts: 154 | I will pull a tire off tomorrow and get some pics.
1955 GMC 100 Series 2
| | | | | Joined: Mar 2010 Posts: 10,279 Renaissance Man | | Renaissance Man Joined: Mar 2010 Posts: 10,279 | GMTK, thank you for the still pics. Hope you weren't offended by my sinking ship on rough seas comment. I have no business criticizing anyone's video/pic posting ability as I am an idiot in that department. Your rearend still looks to me like a GM 12 bolt out of a truck.
Carl
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
| | | | | Joined: Aug 2011 Posts: 154 Shop Shark | | Shop Shark Joined: Aug 2011 Posts: 154 | No offense taken at all! I should have watched it before I uploaded it.
You think the rear end is from a 1955?
1955 GMC 100 Series 2
| | | | | Joined: Nov 2005 Posts: 6,100 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 6,100 | Hy GMTK, my vote is also a newer GM 12 bolt, I'm pretty sure they weren't marking max diameter on drums in 1955. | | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | I have changed my vote to Blazer. Same drums as my 73 had.
GMC drums have quite an offset in the face of the drum.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: Aug 2011 Posts: 154 Shop Shark | | Shop Shark Joined: Aug 2011 Posts: 154 | Thanks guys. After working on the drum brakes and comparing the parts of the brakes to online auto parts stores, it became a little more clear that the rear end is from the blazer.
1955 GMC 100 Series 2
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