The manifolds are secured by a total of 17 studs (or 11 studs and 6 bolts, depending on which camp you want to be in).
The Parts Manual lists them all as studs, but under 3 different PN's (with the related locations vaguely identified in the exploded-view diagram:
Type ‘12’ – 08214-82810 - 10 of (short) - includes the top-most row, where my engines have bolts rather than studs.
Type ‘13’ – 08214-83010 - 2 of ('shorter long') - one of these is clearly located in the diagram as the rearmost stud where the rear engine 'slinger' (hoist) plate is secured.
Type ‘14’ – 08214-83210 - 6 of (long) - used in the locations where the thick 'yoke' washers are used to bridge the flanges of the intake and exhaust manifolds.
Notice how the Parts Manual says there are 18 studs. In fact, there are only 17 studs used to secure the manifolds. I'm assuming that one of the Type '13's is used somewhere else.
Here's the kit that MSA sells (my original studs are at the top of the photo):
Notice the oddball silver stud (the one in the centre - no yellow zinc plating, different overall length from all the others, different length of unthreaded shoulder from all the others.
Here's a closer view of my original studs (the snapped-off stud came out of the engine slinger plate location, natch)...
A couple of observations:
They all have the same threaded length for the end that screws into the head (makes sense, but easy to overlook during re-assembly). The threaded length for the 'engine' end is shorter than that for the 'nut' end, which means that I've got the studs stacked wrong-side up in my photo of the MSA studs.
Once again, one of the 'long' studs is a little shorter than the others and has a slightly shorter unthreaded shoulder. In this case I know it was not from the engine slinger location, but unfortunately, I didn't notice the difference in the long studs until I had them all out on the workbench afterwards, so I can't be sure where it came from. It's possible that my snapped-off stud was also a 'short long' type, meaning that these are supposed to be fitted to both the rear-most and the front-most locations. If that's the case, then the MSA kit is technically incorrect by supplying only one of them. I don't think it's going to matter much for the front-most location, but I'm going to definitely fit my single 'short long' stud at the rear-most location to secure the slinger plate (I have a suspicion that it's made from a higher-strength grade of steel than that used for the plated studs).
Comments welcomed from any of our veteran or professional L-Series engine rebuilders.