Done this before; here it is again (or reason not to worry):
"Let's see, we take out an old engine that puts out maybe 250 lb. ft. torque, backed by a granny tranny with a 7.0 low gear, and replace it with a V8 with, say, 400 lb. ft. torque and an auto tranny with a 2.5 low gear.
250 x 7.0 = 1750 lb. ft. torque to the rear versus 400 x 2.5 = 1000 lb. ft. torque to the rear.
And how come nobody worries about the driveshaft and U-joint as well as the rear end?
Just sayin'!"
