That is certainly a mystery there BV
Being as the thing that seemed to be causing you all the grief was the FMC sleeve of the gearbox .... Is it possible, that gearbox started life in a diesel powered Sierra ???
Sold quite a few diesel gearboxes to petrol heads that want a bit more oomph from their ride
One thing for sure, I know what it feels like to end up spending more than you would have done on an off the shelf option
I guess that is one of the hazards of dealing with the now elderly Sierra .... Very likely to have some mix'n match components !!
Just for the sake of this thread & future reference
My type 9 gearbox is from a 1991 Sierra estate ( Known to be the original box )
My engine is from a early 1992 1.8 Mk5 Escort hatch, Silvertop Zetec & known to be the cars original engine.