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**71CHEVYSHORTBED402** · 03-10-2019, 08:18 PM

Someone gave me the clue to look at the part's book.

http://www.gmpartswiki.com/getpage?pageid=22606

3885614 - Chrome Rear Bumper Bar. 67-72 C-10-20 (Sub, Fleetside) Blazer

3890391-2 - Inner Brackets. 71-72 Ser. 10-30 (Stepside, Fleetside) and more.
Reads excludes leaf springs. Found an NOS on the Chevy site, it’s the bracket folks call “coil spring” inner brackets. NOTE: The same part was used for the front bumper on 67-70 "pick-ups" (excludes 4x4)

3952089-90 - Inner Brackets. 69-72 Ser. 10-20 (4WD) (Pick-up)
Reads Rr. Bumper, which is rear bumper. No web reference found. Possible these are what folks call “4x4” inner brackets.

3891985-86 - Inner Brackets. 68-72 SWB 2WD with leaf springs.
No reference found on the web for this bracket. Not surprising. My Chevy is an outcast

3891987-88 - Outer Brackets. 68-72 SWB 2WD with leaf springs.
Go figure my outer brackets are an oddity? Don’t know why outer brackets would differ, I’ve always heard they’re the same. I have two sets (repop & OEM) and they seem to clear just fine. Maybe there’s a variance for the rear hole in frames, I’ll research.

Ironically there are quite a few hits on the web for this outer bracket. The part number is referenced for replacements. May imply they’re wrong, may imply a lot of things. Been 50 years, stuff gets lost.

3892477-78 - Outer Brackets. 71-72 and more. Ser. 10-30 (Conv., 4WD), Blazer (Stepside, Fleetside) and more. Applies to many trucks. Reads “Aux. leaf springs excluded”. Can’t say what an “Aux.” leaf spring is, but OK.
Found an NOS on the Chevy site, looks like the typical outer bracket. Other than that nothing found on the web.

03-10-2019, 08:18 PM	#2
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,151	Re: Rear Bumper Bolt Pattern Thread Someone gave me the clue to look at the part's book. http://www.gmpartswiki.com/getpage?pageid=22606 3885614 - Chrome Rear Bumper Bar. 67-72 C-10-20 (Sub, Fleetside) Blazer 3890391-2 - Inner Brackets. 71-72 Ser. 10-30 (Stepside, Fleetside) and more. Reads excludes leaf springs. Found an NOS on the Chevy site, it’s the bracket folks call “coil spring” inner brackets. NOTE: The same part was used for the front bumper on 67-70 "pick-ups" (excludes 4x4) 3952089-90 - Inner Brackets. 69-72 Ser. 10-20 (4WD) (Pick-up) Reads Rr. Bumper, which is rear bumper. No web reference found. Possible these are what folks call “4x4” inner brackets. 3891985-86 - Inner Brackets. 68-72 SWB 2WD with leaf springs. No reference found on the web for this bracket. Not surprising. My Chevy is an outcast 3891987-88 - Outer Brackets. 68-72 SWB 2WD with leaf springs. Go figure my outer brackets are an oddity? Don’t know why outer brackets would differ, I’ve always heard they’re the same. I have two sets (repop & OEM) and they seem to clear just fine. Maybe there’s a variance for the rear hole in frames, I’ll research. Ironically there are quite a few hits on the web for this outer bracket. The part number is referenced for replacements. May imply they’re wrong, may imply a lot of things. Been 50 years, stuff gets lost. 3892477-78 - Outer Brackets. 71-72 and more. Ser. 10-30 (Conv., 4WD), Blazer (Stepside, Fleetside) and more. Applies to many trucks. Reads “Aux. leaf springs excluded”. Can’t say what an “Aux.” leaf spring is, but OK. Found an NOS on the Chevy site, looks like the typical outer bracket. Other than that nothing found on the web. __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring the truck from ground up. With assys, the guide accts for 1000s details, OEM identifications & part numbers, written in short order. 700+ images of assm., illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 03-11-2019 at 02:52 PM.