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**71CHEVYSHORTBED402** · 02-12-2021, 03:30 PM

[quote=scrappydoo2k2;8875372]@71CHEVYSHORTBED402 Did you ever get the rear bumper bracket snafu ever figured out? I'm in a similar situation (1970 leaf spring, LWB to SWB conversion, but looks exactly like yours except I have no mounting holes in the frame).

I revised this following a mod.....

Rear sport bumper brackets for 1971 2WD, SWB with leaf springs. The shorter inner brackets are the closest of the two sets available, and both options use the same outer bracket. Some call these shorter brackets "coil spring" brackets, which have a 5" bolt pattern. The rails on a 2wd, SWB with leaf springs are a 5.3" bolt pattern, based off my 1971 C-10.

The front hole on the frame rails of my truck are 6.1" from the rear of the frame rails. I believe the front hole on rails that take a "coil spring" bracket are 6.4", so the coil spring brackets have to be modified to slide 3/10" foward. Simple Modification:

INNER BRACKET: Slot the bracket's front hole 3/10" to rear. Slot bracket's rear hole 6/10" to rear. Cut the front top of the bracket to clear the hanger revit.

OUTER BRACKET: Weld up the hole & drill a new one 3/10" further back. Fit the bumper using the inner brackets, I used studs because.....Fit the outer brackets to see where to cut the bracket to clear the swell in the frame for the hanger.

The bumper is supposed to sit ? behind the frame rail. I thought 8", but perhaps about 9".

After the modification the pitch of the bumper isn't quite right, probably due the difference in bolt patterns. I'll slot the bottoms of the holes in the brackets to lift the bumper some - fitting the bumper to the bed is pending.

02-12-2021, 03:30 PM	#24
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,120	Re: Rear Bumper Bolt Pattern Thread [quote=scrappydoo2k2;8875372]@71CHEVYSHORTBED402 Did you ever get the rear bumper bracket snafu ever figured out? I'm in a similar situation (1970 leaf spring, LWB to SWB conversion, but looks exactly like yours except I have no mounting holes in the frame). I revised this following a mod..... Rear sport bumper brackets for 1971 2WD, SWB with leaf springs. The shorter inner brackets are the closest of the two sets available, and both options use the same outer bracket. Some call these shorter brackets "coil spring" brackets, which have a 5" bolt pattern. The rails on a 2wd, SWB with leaf springs are a 5.3" bolt pattern, based off my 1971 C-10. The front hole on the frame rails of my truck are 6.1" from the rear of the frame rails. I believe the front hole on rails that take a "coil spring" bracket are 6.4", so the coil spring brackets have to be modified to slide 3/10" foward. Simple Modification: INNER BRACKET: Slot the bracket's front hole 3/10" to rear. Slot bracket's rear hole 6/10" to rear. Cut the front top of the bracket to clear the hanger revit. OUTER BRACKET: Weld up the hole & drill a new one 3/10" further back. Fit the bumper using the inner brackets, I used studs because.....Fit the outer brackets to see where to cut the bracket to clear the swell in the frame for the hanger. The bumper is supposed to sit ? behind the frame rail. I thought 8", but perhaps about 9". After the modification the pitch of the bumper isn't quite right, probably due the difference in bolt patterns. I'll slot the bottoms of the holes in the brackets to lift the bumper some - fitting the bumper to the bed is pending. __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s of OEM identifications and part numbers, all written in short order. 700+ images include 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; 03-26-2021 at 01:11 PM.