What is the best tranny for my 99 ext cab 5.3 z71? I have a 4L60E in it now. Can the 4L60E be rebuilt to handle 500-600hp? If not, what tranny should i get?

 

if you plan on abusing the truck pretty good, might as well get a 4L80E.. the 60E is pretty fragile as some say.

 

500+=4l80

 

80E all the way

 

What trucks are the 4l80 out of, the HD's?

 

Ya, the HD have 80's but it's not a direct swap, it actually pretty involved. Its a longer trans, so you have to modify the crossmenber and both drive shafts, plus there is a wiring harness adapter you need and a few other things. Speed Engineering sell a complete kit with everything you need for the kit http://speed-eng.com/store/product_i...oducts_id=7612

You will also have to have the PCM tuned for it also.

 

6l85e.

 

4l80e strong power robbing son of a bitch!!!! just dont get a special made torque convetor like i did.....gm has the adapter for the crank!! mine cost me almost 5k with a low mile used trans..and all the work myself..and the smashed hand from it falling of the jack!!!!!!!!!!! THEY ARE HEAVY!!!

 

$5000 seems prety high to me.

i got a used tranny with extras like dip stick tube, converter cover, tranny mount, flex plate all for $1000. then add ~900 for a good converter(you could go less). $109 for a shift kit, $160 for 2 drive shaft mods(4wd), modified the cross member myself but figure $100 for that, i dont remember how much the harness was, seems like it was $200 with programing but i think that has gone up. i got new lines too and a cooler, figure $150 for that stuff.

total of around $2500 if you can do most of the work yourself. my stock 4l80e with shift kit took me well into the 10's and i think it was the converter that took it out anyways. i would say 700+rwhp in stock form!! then if you do happen to burn one up you can get a super strong one built up from someone like FLT.