KM4A1 transmission interchangeable with KM4A2?

[Ltfdrebbin]

We've got a Kanzaki KM4A1 transmission that was winterized incorrectly and is now ingesting water and as a result it quit working.
I'm having difficulty finding a replacement, but there is a KM4A2 on Ebay. The gear ratio is the same and the bolt hole pattern looks the same. Any idea if this would be interchangeable?

I did reach out to Yanmar/Kanzaki to ask but have not heard anything yet.

Thanks

[Ltfdrebbin]

For anybody in the future that might have this same issue, I got an answer back.

We received your request for information about replacing a KM4A1 with a KM4A2. This will not work. The KM4A1 has a smaller SAE# 5 bell housing and the KM4A2 has an SAE# 4 bell housing.

[skipperpete]

Without delving into the workshop manual for more info to see if this might work, is it possible to simply swap the front housing ( bearing carrier assembly) from your old reversing gear to the KM4A2 and re shim the preloads.