Crank thrust washers.
 

I,m rebuilding my 2.5 engine & as matter of course I replaced all the crank bearings & thrust washers...only 1 thickness available...built 1000,s of engines...never seen 1 with thrusts on only the bottom of the crank...my problem...I have no side clearance...checked the clearance in just the thrust half of the crank casing ... measured the width of crank & then the housing with the washers & every time they measure exactly the same...NO side clearance...do you have to reduce the width of the washers by rubbing them on emery paper...not a very Porsche thing to do.

Yes, consider yourself Lucky, many people have the opposite problem,(too much clearance)

Probably this will sound obvious for you, but just in case: the carrier halves have to be bolted together with the 14 bolts and torqued down to spec. The crank has to be running smoothly and easily. Then you should have a very little endfloat that can be measured with an indicator gauge. And to move the crank sideways you need to push it surprisingly hard because it`s heavy and the seven bearings add a lot of friction.

crankshaft bearing carrier.
 

I know what your saying...I have checked with the 2 halves fully torqued & the crank could turn on tightening 12 bolts...as soon as I tried to torque 13/14 the crank seized & would not turn...I then checked the thrust on the top half only & used a pry bar with a clock gauge...nothing...I have bought a set of cases from a 3.2 of e-bay...hope I have better luck.

There are apparently two styles of thrust washer as my buddy and i found out when building his m97. Not sure if this applies to m96 also

Cankshaft bearing carrier.
 

Quad, Thanks for clearing that up...the 3.2 cases arrived & the first thing I did was drop the crank in the thrust half...set up my clock gauge & he presto 006" end float...but to my disgust the main bearings in the M96/21 cases have the locating tang on the opposite side of the shell...M96/20 on the left...M96/21 on the right...so I have to by another 14 new bearings.

crankshaft bearing case.
 

On stripping yet again my crank case I have found ATF & assembly fluid seeping out from 6 of the main bearing housing...between the steel insert & the alloy casting on the bottom half of the assembly...on close inspection with a magnifying glass it looks like the insert has broken away from the casting... on checking on e-bay for second hand one,s I saw several which looked the same...anyone heard of this before.