[motto]

Hi Chris.
In answer to your question on whether a Stude gearbox will fit in your Chev, the answer is yes and no. These vehicles had a 216 engine in them originally so what engine are you referring to when you say 235? If a splash feed truck engine the 5 speed o'drive Clark g/box from a Stude US6 will bolt to the bell housing but the clutch shaft is very different. What you really need is the g/box from a GMC 6x6 or the clutch shaft and bearing retainer from one to convert the Stude box to that configuration. The rest of the g/box is the same for both GMC and Stude.
To cut it short, the GMC 6x6 box will bolt straight onto the original 216 or a 235 truck engine, everything fits. BUT, if installing this box on an engine to go in the truck in your picture you will have to cut away half of the engine mount cross member. The reason for that is because the 5 speed Clarck box is basically flat on the front whereas the original 4 speed Chev box steps back below the lower edge of the bell housing.
Another thing about the box out of the 6x6s is that they both use a 2 speed transfer case so the speedo drive is off that not the gearbox. There is no provision on the g/box to run a speedo.
If when you say 235 engine you are referring to a Blue Flame, it could be from a car with smaller clutch and bell housing.
I can supply an original NOS clutch plate should you want it.
David