may soundl like a silly question but i don't know too much about Fords (yet)

I have a Sierra Sapphire 1.8 LX, a reconditioned CVH engine. I'm taking the engine out and selling it as i'll be dropping in a 2.9i V6 from the XR4x4.

I want to keep the car RWD, not 4X4, so.. could i use the gearbox from the 1.8 on the V6?

Any help would be good as i'm looking to sell the engine soon and want to know whether to sell it with or without the box.

Cheers.