Alright, it’s been like 3 days since I’ve bought anything and I needed my fix, so I found a verrrrry interesting pair of 454 valve covers for $120 shipped! Does anyone recognize these? In case you’re not aware, the L29 (your typical Gen VI Vortec 454) had a fairly unknown twin, the L21, which came in the medium duty chassis trucks for a short period. These 454’s came with some interesting LS-like features, such as a 24x reluctor wheel instead of the typical 4x, coil-near-plug system including the unique valve covers, and a capped, gutted distributor for the 1x cam signal. It ran off an early 97-98 LS1 PCM. Pretty interesting and rare setup!
And this is the L21 in the wild. Note the staggered coil mounting under the throttle body for clearance, which differs from the 8.1L.