i have a 91.5 w250 with a non lockup overdrive trans that is smoked, i found a lockup overdrive trans that im told will fit but i would to know if there is anything i need to change before i get this trans or just rebuild the one ive got

 

The lockup trans has to be from a diesel. It would need to be from a 94/95 truck. The 96 and up were electronic trans. You would need a stand alone controller for them.

You would also need the engine adapter and the starter. The engine adapter is about 1.5" deeper to allow for the lockup converter.

 

where would one be able to find the adapter and starter

 

You could check the classfields here, eBay, craiglist, or try to find one at your local junkyard. There may be a website that sells these items though.

 

the adapters are always on ebay. I look like once a week.

The starter you could just buy new froma parts store, buy one for like a 94 or95 ram 2500 with cummins/automatic. It will be pricey but it will be new.

 

And update to the newer verison of flexplate.