three speed gear ratio

[SuperDutyScaler]

i was reading a few post where it reads that the semi gearbox has lower ratio's than the F-350 gearbox? im turning my F-350 into a pulling truck and since my big rig isnt done yet i was going to see if i can put the semi gears into my F-350 and try some motor setups. is this true and can they fit into each others gearboxes??

[Tamiya Cowboy]

All the grears are the same I am pretty sure as I have a set of each here and they look the same. I have not head the semis are lower geared..

[Stepside]

I think it may be quite the opposite. I think the highlifts are geared down due to the large spur gear that the engine meshs with.

I believe Paul is right, the internal gears are identical on the three speeds. I think the only difference is the large spur gear on the front of the highlift trans.

[tc1cat]

I agree with Stepside. My Studebaker build had an F350 tranny in it for 4WD and was much slower than any of my semis with the same motor in them in the same gear.

[Espeefan]

The big rig and Highlift transmissions both use identical internal gear sets for 1st, 2nd, and 3rd gear. It wouldn't make sense for Tamiya to tool up special gears for the Highlift, so the parts carry over. What is different about the transmissions though, is that Highlift has an added transfer case to the rear, and the gears used in the transfer case portion provide an extra reduction that the rig transmissions lack. There could also be a difference in spur gears or pinion gears as well, but internally, excluding the transfer case of the Highlift transmission, they are identical in design.