Thanks for the quick reply! we will probably not get to pull the engine for a few days yet. It is my brother's machine and he bought it knowing it would need the engine rebuilt or be re-powered with another engine. My brother has a hearing problem & is not very savvy on using a computer, so I am helping him do the research, checking things out & helping him get it running again.We have both done mechanical work on vehicles & heavy equipment but are not expert at it. Advice & help is much appreciated! Thank you!The FD-7 was in the 75-84 HP range so a 4bt would be plenty of power. Could possibly even use a 4b which is non turbo. As far as fit I'd think it could be done. Most likely would need either a SAE2 or SAE3 transmisson/clutch adapter on the 4bt. That would be no problem. Don't know that we've had anyone do a comparable swap. Have you got the old engine out of the dozer? If so, might do a bit of measuring to see if any problems exist. You might have to be a pioneer on this swap.