tranny help

[slow69]

I searched the past posts and couldn't find the info so here's the question.

What is the gearing differences between the 4 spd granny gear (sm465?) and the 3 spds in our trucks? Is the gearing the same except the 4 speed has the extra granny gear?

I am trying to decide whether to buy one but if there isn't much of a difference from the 3 speed that I have, I don't know if it's worth the 200 or 250 it will be with shipping.

Thanks guys.