GM automatic numbers are decoded as:

4L80E =

4 - four speeds, can (in theory) be either 3, 4 or 5 (and some day perhaps 6?)

L - longitudinal, can be a T for transverse (as in front wheel drive)

80 - Torque or power rating for the model. Not an absolute value, just relative to other models. Could be 40, 60, 80 (and perhaps some day 100?)

E - Electronically controlled. That is it is controlled by a computer not a mechanical device.

A 4L60E is very similar to a 4L80E in basic design. The control system is very similar (probably the same basic TCM with different programming and possibly different sender circuits). A 4L60E won't handle the torque of a big engine, however. It is designed for either bottom-end V8s or six cylinder engines.

Peter H.