d100 manual trans question....

i have a 70 d100 currently a 318 with 3 speed manual in floor. found a 68 d100 with a factory 4 speed. my question is does anyone know if the 68 would be a granny gear with 3 speed? if not i would like to change it for my 3 speed. truck is currently sitting on the ground and couldnt get to it to see any numbers. thanks. ive also posted this on sweptline.org but info can be very slow when questions are asked and this truck will be crushed soon.