2. Middle. Four short 10m studs out of the cases, that hold the barrel to the cases. Then there's 8mm studs out of the top of the barrel to hold the head on (125s have four 8mm studs, 175s have six).
All monoshock DT125/175s, YZ125D/E/F, IT125, IT175D/E/F have this set-up.
Beware the 85+ DT175 top ends - they run a shorter rod and different piston.
there are two different crankcases in this group, the size of the transfer ports are larger on the later DT175 compared to the earlier monoshock DT's the later DT cases are also the same as an early IT175.
the IT125 shares the same crankcase as the early monoshock DT with the smaller transfer ports. I'm unsure of what rod it uses though as I've only just started pulling my 125 apart
Cheers!
Leslie