5 Speed conversion for 1946 K5 Truck

[TrevorFry]

Hello from Australia!
My first post question here - seeking some advice / guidance please.
I have a 1946 K5 truck, with the original 233 Ci Green Diamond engine, into which I would like to swap a perhaps more modern IH (1st preference) gearbox with an overdrive & perhaps some synchros.
My research & reading so far seems to be pointing me towards a T34 gearbox which brings me to my question about compatibility of bolting up the T34 to the Green Diamond- I don't seem to be able to find any writings on this swap although I expect that I would not be the first to contemplate this upgrade.
Appreciate your thoughts / guidance / experience on this or any alternative.
Cheers
Trevor

 

[Robert Kenney]

The t34 35 and 36 are the same on the outside and came behind the SV series of engines. I don't know about those transmissions being offered behind the other IH engines. Maybe some one else can offer that up.

The most prevalent application you are likely to run into in the SV version. You might start by finding a cheapo SV bell housing and see what an adapter would require before buying a trans and it's bell housing.

 

[Greg R]

Not much on the early sixes, particularly Green Diamonds. I think their bellhousings follow the SAE format. I do not know what size a GRD 233 would have. If you wanted OD without a lot of fabbing, maybe look and find an F51 5 speed transmission. It's old, but what IH offered on the KB6 and COE. OD was used more on trucks with low ratio axles. Speed wise you didn't gain much between a low ratio such as a 6.2 with OD and a 4 spd on one with a 5.28 rear axle, maybe 5 MPH difference at rated or governed engine speed. Overall the OD ratio was around .75:1

Another thing to figure out is the transmission input shaft length and spline. The spline can be matched to a clutch disc hopefully at a clutch/driveline shop, but the housing and shaft length will take some figuring too.

OldIHC.org may have some guys with more knowledge.