Man, there's only one way your 18RG could have weighed 175kg, and that's with 40kilos of kid sitting on it
We weighed my brothers 18RGU just before we put it in the car (inc. carbies and exhaust manifold and oil) and it weighed around 135kg (no aircon)
the 18RC wieghed about 140 when we took it out, may have had aircon, maybe not, not sure when we took that off.
The 18RGs are liftable in this state by two guys (albeit uncomfortly) so it can't have been 175, with my injury record, I'd have broken for sure