I believe the air cleaner studs have larger threads at the manifold. If you were to replace them with all thread, you may have to drill the airbox lid to pass them. If you're doing that anyway, you could try stacking a pair of air filters with longer studs. It makes the CUCV noticeably louder, faster, and depending upon how much blow by you've got, smokier. Two filters fit under the OEM hood and if you don't like it, it's immediately reversible and you have an extra filter for next time.