1999 Dip gearbox cooler

[Hitechpete]

Hi, I have a 1999 Monaco Diplomat 36' Motorhome. My radiator is collapsing and I am in the process of having a new radiator built. As part of the process I am removing the internal heat exchanger/cooler and propose to install an external cooler. My questions are: what size does it need to be, and what flow rate should it have, so as to provide adequate oil flow back to the gearbox.
Allison are not proving to be very helpful answering my questions.

[BFlinn181]

Allison builds transmissions. Your inner cooler for intake air and transmission cooler were designed to meet engine specifications and need. Check with engine or chassis maker for the numbers you're looking for. Moving cool pack to a new location means more fans and venting of heat, which will require more power from the engine. I'd think of putting it back the way it was with new components, not re-engineering a carefully thought out original design.

[Skip426]

A belated Welcome to iRV2.

My 99, w/ Allison 3060, has an external oil to water cooler, in the lower rad hose, that may not fit if you have a rear rad.
If you have a side rad, I can provide pictures and P/N's if I can find any.

[Hitechpete]

Sorry I forgot to mention that it's a rear radiator.
I believe that Monaco themselves decided to fit external transmission coolers following their debacle with aluminium radiator failures; resulting in gearbox failures due to coolant/transmission fluid mixing.