Ok I have some numbers from a Ford 5 speed Id like to identify.
These numbers are from the metal tag bolted to the extension housing.
839T FE
FOG 7F 29G
Can someone please identify this box, ratios and the like would be great but really all I need to know is just what is this box.

Thanx in advance

a good question, is there a register of gearbox parts codes?

Mark the input and output shafts with whiteout, select 1st gear. Turn the output shaft one complete turn.
Tell us how many times the input shaft turns. You'll most likely find it will turn 3¼, 3½, or just under 3 turns.