[KTL]

The conical/top-lock/deformed thread nuts seem to be preferred due to their higher resistance to loosening. If you do a dry torque test on a conical vs. nyloc, you can see it takes less torque to turn the nyloc.

But I don't think it really matters. These spring plate bolts are torqued rather tight (90 ft-lbs I believe?) and their tightness is being maintained by the stress/stretch in the bolt, not the locking mechanism.

Incidentally I was playing with some conical M10x1.5 nuts the other day. I put one on a semi clean stud (head stud that I wire brush cleaned of the threadlock remnants) and it only required ~25 in-lbs to turn. That's only 2 ft-lbs. So the point being is the grip on the bolt by the conical locking is not super duper tight.

Actually I replaced all the trailing arm-to-spring plate bolts on my '87. The originals showed a lot of wear/bearing on the shanks so I thought it'd be good to replace them. I didn't want to blow a bunch of money on ordering original M12x1.5 Porsche bolts individually or buying 50 of them from Metric Multistandard. So I bought a box of ten M12 x 1.75 bolts in 10.9 property class from McMaster-Carr. Couldn't find any class 10 nuts in conical so I used nyloc. Has been working just fine, put to the test on the track numerous times!