http://www.fastfordmag.co.uk/files/old/FAF243BUYER.pdf
Can't be sure if the shell is the same, the suspension, steering and brakes are different, so in theory that could be just bolt on/swap over, but
Potentially it might have different mounting points?the RS broke the mould with a rearranged front anti-roll bar and tie-bar set-up
Shell authenticity does affect value by the looks;
So yeah, I think in the ford fratenity, it looks like you would definitely struggle (very hard!) to claim it is an Rs1600i with a zetec engine and the wrong shellGetting lumbered with a ringer or a spruced-up XR is bad news. Make sure all the numbers tally with the V5 (look for WFOBXXGCAB followed by either C for 1982 or D for 1983 and then the five digit engine number) and that the RS was actually made when the logbook says.

What I didn't realise/hadn't given credit to it for before reading that article (because I struggle to give credit to such things from my essex youf) was how different/improved it was from the standard car and the xr3...