Main bearings question

[Sideshowkev]

Hi, I have just bought a set of main bearings for a 3.9 Rover V8 only to find out the engine I bought is in fact a 3.5 after looking up the engine number. (Second hand engine out of a Disco 1 with a 3.9 plenum)
The bearings supplied fit apart from the centre one which will not allow the crank to drop in as the sides are too wide.
The existing bearings had a single thrust face and a plain bearing and the new bearings come with 2 sets of thrust faces.

Bearing

[paul c]

I thought it was later engines that had only a half thrust bearing. Some engine parts suppliers sell the half shell separately.