will a rs 1800 gearbox fit a fiesta rs turbo

 

The RS1800 was a Fiesta,So the gearbox will fit a Fiesta RST.They are the same.The gear ratio inside maybe different,But you will not notice a massive difference.I can't remember if the 1800 had an LSD though.
Tonto

 

same gear box , same ratios and neither had a LSD

better off finding a S2 escort box with LSD already in