I have a 1997 Sierra 2500 RWD, with a Vortec 5700 and 4L80E

im wondering if i can put a LS1 in and use the stock transmission, now considering the original Vortec 5700 only gives off about 230 horses, shouldnt the LS1 give me more towing power?

Just wondering.

 

but how much torque is it making? HP does not matter with towing.

 

I would recommend the 6.0L or 8.1L engines over the LS1 for towing. Your transmission has a plastic or aluminium dust shield for the torque converter, this dust shield does not bolt to the engine to provide any support for the transmission. On the newer trucks with the LS series engine the bellhousing for the transmission is missing the upper right hand side mounting bolt, this is where your dip stick attaches too. The engine oil pan on the LS1 and 6.0L also bolt to the transmission dust shield this provides more support for the transmission. If the dust shields have the same mounting holes, then all you need is the dust shield off a newer 4L80E transmission. For the rest of the parts like wiring harness, motor mounts and other stuff check out Street and Performance.

Another good website is LS1 Trucks.