I am working on a project that originally had an X Drive installed and I have a Bravo 1 with an IMCO extension box I am planning on installing. I looked through the archives on this site and found some information but guess I still have questions whether it can be installed in the existing location or will the transom need to be redone. Any input would be greatly appreciated, thanks in advance !!

Well it depends on the boat, the box, and what you're looking to achieve. I'm far from an expert but we will start at the beginning. A bravo x and a traditional bravo 1 are the same length. So bolting it directly to the transom you'd have the same propshaft height.

Next is the box, if it's a straight transom boat then a neutral box you wouldn't need to modify the transom. Even an angled transom you wouldn't need to redo the cutout but with a natural box on an angled transom your propshaft would be approximately 3" lower. If it's a +3 box the cutout will not need to be modified however the engine mounts and exhaust holes will have to be raised 3" to account for the raise of the box.

I believe it's the stellings box that have the driveshaft u joints where your engine mount retains the same location and the driveshaft angle changes in the box? (Don't hold me to that) however they don't make the stellings boxes anymore that I'm aware of.

That's just the tip of the iceberg really. If you post more specifics of what you're looking to accomplish and which boat you're running I'm sure guys around here can point you in the right direction of propshaft height that would be optimal for your setup.