Im Going to dyno my 76 vette tomorrow morning but i dont know what the gear ratio is i have an l48 with a 4 speed if anyone knows it would be great thanks

Since the ratio could have been changed since the car was new, use the following method. Jack the rear wheels of the ground. Put a mark on the drive shaft (chalk works well) inline with one the the rear end housing. Put a mark on outside of the tire so it can be seen when one turn is complete. Put the car in neutral and have a friend rotate the tire one revolution. While your friend rotates the tire count the number of times the drive shaft turns. For example, if the shaft turns 3 and one half times, the ratio is 3.50, etc.

Good luck,