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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: 87V20Kansan on April 24, 2014, 12:00:49 am

Title: 14 bolt rear
Post by: 87V20Kansan on April 24, 2014, 12:00:49 am

Will the 14 bolt FF out of the '88-'98 trucks fit under our trucks? They sure are a lot more plentiful at the pick and pull around my part of the world.  I know that the mounting pads for the springs are in different locations and pinion snout length differences may alter my driveshaft length. I can handle all of that with no issue. Is the axle flange to flange width even close? I can never find a 73-87 14 bolt FF in a yard to even measure. I sure would like to make that work rather than buying and gutting a 1-ton squarebody. Keep in mind that I m running the H1 wheel with a 2 inch spacer already. I can grow the flange widths up to about 4-1/2" inches from the K20's 9.5 inch 14 bolt and lose the spacer if I need to.

Title: Re: 14 bolt rear
Post by: Da67goatman on April 24, 2014, 03:42:28 am

Spring perches are farther apart on 88-98.

Title: Re: 14 bolt rear
Post by: Engineer on April 24, 2014, 08:08:34 pm

Wow, I have been looking for a 14-bolt FF for my '94 K2500 and can't find one anywhere. The 73-87 14-bolts are all over the place around here. And never more than 2-3 phone calls away.......

Title: Re: 14 bolt rear
Post by: 87V20Kansan on April 25, 2014, 12:05:42 am

Maybe we can make something happen Engineer. I have them show up 8 out of 10 times I happen to go to the yards around here. I'd love to have a direct swap into my truck  with 4:10 gears.

Title: Re: 14 bolt rear
Post by: pholliday1 on April 26, 2014, 09:29:37 am

You mentioned" pinion snout lenght" pretty sure that's a nonissue as I believe there all the same

Title: Re: 14 bolt rear
Post by: 87V20Kansan on April 28, 2014, 09:05:11 am

Quote from: pholliday1 on April 26, 2014, 09:29:37 am

You mentioned" pinion snout lenght" pretty sure that's a nonissue as I believe there all the same

Really? Interesting. I would have assumed there would be a difference in the 10.5 vs. the 9.5 inch rear ends. So in a swap from 3/4 ton to the square body 1 ton FF, you don't have to alter driveshaft length?

Title: Re: 14 bolt rear
Post by: timthescarrd on April 28, 2014, 12:01:23 pm

The 9.5" Semi-Float rear and 10.5" Full-Float rear have different pinion snout length.  But th3 73-87 14 Bolt FF and the 88-98 14 Bolt FF are the same.  So if the 3/4ton came with a semi-float 14 bolt, the drive shaft may need shortened when changing to a 1ton full-float. 

Some K20's came with the 14 bolt FF

Title: Re: 14 bolt rear
Post by: 87V20Kansan on April 28, 2014, 08:18:50 pm

Quote from: timthescarrd on April 28, 2014, 12:01:23 pm

The 9.5" Semi-Float rear and 10.5" Full-Float rear have different pinion snout length.  But th3 73-87 14 Bolt FF and the 88-98 14 Bolt FF are the same.  So if the 3/4ton came with a semi-float 14 bolt, the drive shaft may need shortened when changing to a 1ton full-float. 

Some K20's came with the 14 bolt FF

That sounds exactly as I hoped it would. Now why didn't I get lucky enough to buy a K20 with  a 14FF?  ;)

So are the track widths the same from the 2 different generations? That is the real question at hand. Will the wheel and tire package get shoved way outside of the body line with a later model rear?

Title: Re: 14 bolt rear
Post by: pholliday1 on April 28, 2014, 09:05:15 pm

Thanks timthecard that's what I meant