Why is my shop so reluctant to do a 10 bolt to 14 bolt swap?

[alpinecrick]

They were on 1500’s with F44 option. My buddies and my former 96 K1500’s both had 9.5 SF from factory.

You are correct, forgot about the F44 option on the 1500's.

 

[Boots97]

F44 gas 1500's got 'em too. I parted a few.

OP, you'll want new u-bolts. I know this doesn't solve your u-joint problem, but you don't want to re-use u-bolts; they are TTY (torque-to-yield) so they stretch as you torque 'em down. They'll "seem" fine on re-use but they may not torque correctly the second go-round. Not something you want to risk.

Richard

Yeah I'm not super comfortable with reused U bolts, but I can take care of that later. The shop is 3.5 miles away and I don't do a lot of long distance driving so I can live with reused U bolts for now, but they'll get taken care of when time allows.

 

[Boots97]

Update #3 on the truck: Truck is mostly done. I'm picking it up tomorrow morning. They noticed a slight vibration on deceleration and they believe that the driveshaft is a touch short. The service tech recommended me to get the driveshaft lengthened by 1 1/2 inches. They don't do that kind of work (obviously) and are going to give me a number on my invoice to a shop that lengthens/shortens driveshafts. I plan on calling that shop once I pick up my truck.

 

[Boots97]

Update #4 on the truck: Got my truck a few hours ago and it runs and drives great! There is a VERY slight vibration on deceleration but I understand why the shop wanted to warn me about it. I called the driveshaft shop which is 45 minutes away and they said they could see my truck at the end of August. I'm OK with that bc my truck drives well enough for my liking so I can wait.

 

[RichLo]

Did you re-use the driveshaft that was originally in the truck? or did they find one from another donor vehicle?

 

[Boots97]

Did you re-use the driveshaft that was originally in the truck? or did they find one from another donor vehicle?

I bought another driveshaft off of eBay thinking that it would work. The hole for the U joint to the rear axle was off so they sent it to a driveshaft shop to have it redone. It works, but is a touch too short hence the mild vibration. They recommended me to get it lengthened which I plan on doing in a month from now.

Here's the link for the driveshaft.

New Rear Drive Shaft Assembly for Chevy GMC K1500 K2500 Auto Trans 15004110 | eBay

GMC K1500 PICKUP 1994-1999. CHEVROLET K1500 PICKUP 1994-1999. CHEVROLET K2500 PICKUP 1994-2000. GMC K2500 PICKUP 1994-2000. Drive Shaft Length (In): 70.875 In. Drive Shaft Wall Thickness (In): 0.083 In.

www.ebay.com

 

[RichLo]

I bought another driveshaft off of eBay thinking that it would work. The hole for the U joint to the rear axle was off so they sent it to a driveshaft shop to have it redone. It works, but is a touch too short hence the mild vibration. They recommended me to get it lengthened which I plan on doing in a month from now.

Here's the link for the driveshaft.

New Rear Drive Shaft Assembly for Chevy GMC K1500 K2500 Auto Trans 15004110 | eBay

GMC K1500 PICKUP 1994-1999. CHEVROLET K1500 PICKUP 1994-1999. CHEVROLET K2500 PICKUP 1994-2000. GMC K2500 PICKUP 1994-2000. Drive Shaft Length (In): 70.875 In. Drive Shaft Wall Thickness (In): 0.083 In.

www.ebay.com

Ok, that makes more sense now... May I please recommend that you also bring your stock driveshaft in to the driveshaft shop. They may find the stock one could be more cost effective for you than to modify than that aftermarket one.

Either way, I would let them be the judge on what to do.

 

[Boots97]

Update with the truck:

So the driveshaft shop told me that these Chevy/GMC trucks that came with aluminum driveshafts will not balance well with a steel driveshaft. They've seen unbalanced driveshafts shake trucks to death resulting in airbags going off. I gave the shop my original driveshaft and they told me that it's dented (it is, but not badly) and they offered to make me a new aluminum driveshaft and install it for $900. I don't have that kind of money rn so I just picked up my truck and brought it home. I ended up using a Precision 448 conversion U joint on my original driveshaft and pulled out the eBay driveshaft and reinstalled the original driveshaft with the conversion U joint and bolted everything back together. Truck runs great with no vibrations and I love my not rusty rear axle with many more miles to come.