does anyone know if the bellhousings are interchangeable between the 833OD and the NP435? not sure if the bolt patterns at the back are unique or specific to each trans or if they are universal?

thanks

They are not...This is a side project I have been figuratively working out...the Bearing Retainer hole is the same to receive the 5.125"retainer
that the NP 435 and A-833OD has (and the late model A-230). My interest is in making a conversion plate as the 11" slant flywheel uses the same 11" clutch that some 340/360 and 383 equipped cars used (which means a cheaper easily available clutch that will engage and won't wear as quickly or fade like the 9 1/4" and 10"...the NP435 has an almost rectangular pattern similar to the A-230 bellhousing but much "wider"...
the A-833 has a slighly irregular 4 bolt pattern and one of the bolt holes if off the "flat" of the Np435 mounting pad...so either some welding has to be done to the NP bell then a redrill and thread to make that "ear" work, or you have to make and adaptor plate with a set of chamfered flat head bolts for the plate then a set fof "studs" for the the A-833 to bolt to...

I've been mocking this setup up for a while trying to get some measurements going for a prototype...there's more interest in other adaptor (LA-727 to slant six) than there is for this one currently.

-D.Idiot