Hi everyone,
I just bought an 04 2500 hd 6.0 with 4l80 , I already have a 99 1500 with an lq9 and a FLT level 5 4l80 with PI 2600 stall with 20k or less miles on it. I am planning to swap the transmissions and sell the 1500. My question is will the level 5 4l80 with its hard shifting blow the rear end to bits? On the 1500 many years ago a 4l60 from FLT blow the stock g80 rear end straight to hell in just a few days. The HD has 152k miles on it right now mostly highway. Factory tow package no goose neck or 5th wheel has been attached.

Should I Swap? I would feel much better keeping the FLT trans as I have 5 THOUSAND DOLLARS IN IT and one thousand in the verter.

2500 hd is crew cab short bed
1500 is reg cab short bed.

 

What rear did you put in your 1500 after you blew the first one? I think the 10.5 in the 2500HD will be up to the task.

 

I replaced the one in 1500 with an auburn posi and gears.

 

Why does it shift?

If its the valve body, then maybe have it reworked to shift to your liking, then swap it in the 2500.

In all reality the high mile 80e will prob last a long while, but hell you got a kick *** converter and a trans you spent a lot of money on, might as well swap !

Hopefully V. B. had his hand in that trans and i would def. keep it!!

BTW what are your plans for your new ride?

 

The new ride is going to remain stock except for stereo and window tint. I might but not likely have it tuned. I am over hot rodding. I want comfort and low noise levels.
I do love the good firm shift in the FLT trans. The HD is mushy like stock. I pulled my enclosed trailer with it tonight and the trans is fine other than being normal stock.

 

I would definitely swap. Bear in mind that your HD has a huge 10.5" 14-bolt; it is a much tougher unit than the 10-bolt you blew the G80 in.

 

Why don't you e-mail or call Chuck? It is a FLT.

 

The real question was about the rear end. I think I will shoot them an email as they are always super helpful.

 

With over 150k mi on the stock rear end, it's only preventative maintenance that I can see it this point.

 

That is a valid point; the rear might need a rebuild at some point soon anyway. However, I really don't see that as a reason not to swap your built trans to your new truck. A new G80 and rebuild for your rear is much less money than you have in that trans.