i whipped the L18 and four speed out of the 180B, changed the gearbox, and put it back in in about 2 hours. that didn't include draining the radiator, removing it, taking the battery out, unplugging the electrics, undoing the exhaust headers etc. i'd allow about another 2 hours for that, and about another 2 to hook it al up.

so yeah, half a day easy. get a mate to help with the engine itself though, it's a misson by yourself.