Narrowing rear end

[jj72c10]

I know the proper way would be to assemble the bed and measure from there, mine is in pieces and just checking to see what anyone has done. Have a '72 shortbox. I have had the bedfloor cut back to the frame and tubs widened to look stock. I have 15 x 12 rims with 4.5 backspace (want the deep look). My tires are Mickey 31x16x15 street radials. I am guessing 3" to 4" off each side. Plan is to drop the rear 6.5 to 7" and I would like the boxside to drop down over the side wall. Who has done it, is there a tried and true amount to shorten. The rearend is the original '72, will be installing new moser housing ends and getting rid of the c-clips. Any info would be great!

Thanks,

Jeff

[RexDodge]

Just to be clear...you are wanting to narrow your 12 bolt housing?

[jj72c10]

Yes, with the 4.5 backspace I know it will push the wheels too far out. Everyone running 15 x 12 seems to have 7.5 backspace to work without narrowing factory rear. So I am guessing 3 inches per side for sure. Wanted to find out what anyone else has done.

[RexDodge]

I have narrowed a 12 bolt. You will want to determine what axles you will run and then narrow your housing to fit. With the Moser ends it's easy. I measured and calculated my width over and over to be sure of my cuts...there's no going back . I rented a 3" pipe cutter, cut the housing, pulled the spool, ran a broom stick handle through to line the bearing/Moser ends up (lol, a broom stick handle) and welded it up. Chamfered the ends and did a triple pass with good penetration. Passed NHRA tech no problem! I ran that rear end in a tube framed Chevy II (62) that ran in the 10's. Many passes over a 6 year span and no issues. Motor sucked a valve and wasted too many parts for me to afford the fix so i sold the rolling chassis. The new owner dropped in a big block and has been running the same rear for 4 years now. You can do it...

[lolife99]

Mock up your mounted wheel/ tire combo inside the bedsides.
Set them where you have about 1" of clearance for body roll.
Measure between the two wheels to get the EXACT width of your rearend.
Anything else is just a guess.
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[mbgmike]

What do you need to know. We narrow rear ends and respline rear axles. Just for info you are close to Moser Eng.you may as well take it there. Contact us if you want to take it to Moser. We are dealers for them. They will narrow the housing for around 150, axles resplined for around 140.00. about 300.00 +/- for your rear end narrowed.
Just from experience you will probably be around 3 to 3.1/4 inches off each side