Now that I think about it some more you might have a pretty late model (01-07?) GM only ZF 6 speed as used in medium duty trucks.
I think the similar ZF 6 speed used in the GM pickups had integral bellhousing and the medium duty transmission was without bellhousing.

If it is, and before you do away with the transmission, I'd be interested.

Grigg



1951 GMC 250 in the Project Journals
1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-