Thatsilveradoguy

Hey guys so I'm new to the forum and website but I hear this is the best place for promising answers so here's my question I have a 99 2wd Silverado extended cab with a 4.8l bolted to the most famous 4l60e transmission I want to ditch the 4l60e and run a 4l80 but I'm not sure if it'll fit the bolt pattern to the back of the engine block and will this swap actually work on a stock engine the only upgrade is a cold air intake

B52bombardier1

What vehicle are you moving stuff into? The 4L80E might require floor pan surgery. Will almost certainly need a change to the drive shaft length.

Rick

LLLosingit

iTrader: (4)

yes it will bolt right up with the correct flywheel but you need to modify the harness and tune and possibly change the crossmember. If its a stock engine then I would just upgrade the 4l60

He says it's a 99 silverado.

Thatsilveradoguy

Do I need a 4l80 flywheel or a conversion flywheel I'm not exactly sure how to actually do this and it's for my 99 Silverado extended cab id love to get the truck back on the road properly hah still runs on the 4l60 with 1st and second gear I can do about 60 in second does that mean that I have a built trans i just broke or no ???

brandon6.0

iTrader: (32)

If it had a 60e originally u will need a 80e flexplate with spacer.

will need to move crossmember back 6"

U need a 80e yoke, with a napa 447 u-joint

Extend rear trans line like 12". Rubber works. Ive used it before without issues.

Your stock drive shaft will work. Ive always reused them.

U will need a segment swap into your tune. And u will need to add the front vss into the ecu. Not your sure witch pins. Also need to move some wires around in the main grey trans connector. U can google it.

Seems like alot, but the swap is worth it with any big power or power adders!