Besides the engine itself, I believe the only other thing that must be changed is the tune on the pcm. Both models use the same pcm with different running calibrations.
Even though the 4l60E from the l99 will work with the lt1, I imagine it's built to a lighter standard than the trans that came with the lt1.
Now after having said all that, what you have to do depends on what model and year the lt1 came out of. As an example, if you took a 93 f-body lt1, you would have to change the throttle body, new opti harness, swap in the 2nd knock sensor, etc.
So to be more specific on exact changes needed, let members know what year and if it came out of f, b, vette, or fleetwood.
Even though the 4l60E from the l99 will work with the lt1, I imagine it's built to a lighter standard than the trans that came with the lt1.
Now after having said all that, what you have to do depends on what model and year the lt1 came out of. As an example, if you took a 93 f-body lt1, you would have to change the throttle body, new opti harness, swap in the 2nd knock sensor, etc.
So to be more specific on exact changes needed, let members know what year and if it came out of f, b, vette, or fleetwood.
