I have an 84 Montero 4x4 the motor is cooked(G54B). Does anyone know if any other motor will bolt to the 5 speed bellhousing or if there is any adapters available.

That G54B in your Montero is the same engine thats in the Starion and Conquest. Since its relatively the same rwd 2.6 G54B engine this swap should work for you. I've read on some of the StarQuest sites that some are swapping in the DOHC 2.4 4G64 rwd wide blocks. These came in the Mighty Max and I believe in some later Montero's. These wide blocks are rumored to bolt to the G54B 5-speed bellhousing in the StarQuest cars. Also some are swapping the rwd DOHC 2.0 4G63 narrow blocks and the trans (narrow block will not bolt to G54B pattern bellhousing) into the StarQuest cars with minimum modification to the engine mounts. Again the 2.0 narrow blocks came in some Mighty Max pick-ups. Of course, the wiring and ecu and ect. has to be swapped over for these 4G engines to operate. I'll post some sites for you.

I have an 84 Montero 4x4 the motor is cooked(G54B). Does anyone know if any other motor will bolt to the 5 speed bellhousing or if there is any adapters available.
In Australia there were conversion systems available to fit 3.8 liter V6 engines into that model Pajero. The engines came from Holden commodores which are a GM vehicle and the engine is a Buick fuel injected unit that puts out between 140 to 160 kw depending on the model used. You could buy part or all of the kit depending on what you could make yourself. Buying the whole kit got a bit expensive when I looked at it. The other issue with it was engine rev's at hwy speed, 3200 revs@ 110 kph, a bit high for fuel economy in a V6. I understand that taller aftermarket overdrive ratio's were available but I never went looking for them. If you are interested I could try and find more information.