We once had chap in to do a clutch on a zetor crystal.... Tractor , weighs about 5 tonne , as with most tractors the engine unbolts from the gearbox just Infront of the cab , then with appropriate jacks an a bit of flat concrete the two halves roll apart, remove clutch an replace , then roll the two bits back together an stick all the bolts back in. He had it all done by lunch time. I've done a few on smaller tractors. Easiest was a 1960s Nuffield. , remove diesel tank and steering column and there was a clutch cover to lift off, that age JCB,s used the Nuffield skid unit but you had to. Stand on your head in the cab grooping under the dash/diesel tank that was part of the chassis.