I'd guess an RAC van would have heavy duty 'Dana' axle and IIRC you need a tool to spread the axle casing to change the diff. You can get the axle ratio code off the vin plate, or if you know the reg, Ford ETIS if you know someone with a log-in.

Only thing I don't like about Movanos is..they're French. Mate had a Movano that the injectors failed and they were seized in the head, think he scrapped it in the end as it would have needed another engine.

Transit's aren't without their faults but the later 2006> don't have as many fuel pump/injector issues as the older ones.

I do have one in bits at work at the minute, 2011 2.2 fwd with no oil pressure, the oil pump drive/chain/guide etc lay in the bottom of the sump, only 48k miles! New engine and turbo (turbo seized and the securing nut for the shaft was in the intake pipe).