Are you trying to keep a 4x4 going using parts from a 2x4?
I suspect there's a lot more different than you'd imagine, but my Haynes doesn't cover it.
Porter might.
I suspect the cheap (parts) option would be to buy a fully working, but rusted out 2x4, and transplant:
engine
gearbox
driveshafts
font hubs (maybe even the struts and brakes)
gear selection mechanism
and drop the prop shaft off the rear axle.
It would have to be a truly wonderful, fully intact, rust free shell to warrant that sort of effort.
I hope I'm wrong :I
Pete might be along in a while - he'll probably know better
This maybe to far for u to travel but there is a panda 4x4 being broken at a breakers yard just off the A12 half way between chelmsford and colchester. most bits were still on it today including engine gearbox drive shafts....there phone number is 01376 583592. if you ring them they will give you directions how to get there.