look at DusterDaves jeep thred.
he got the older LA alt brackets but they would not fit the mag heads
he made his own brackets to fit mixing mag-LA stuff.
also look at dakota Dons post on serp bet on LA engine.
you need a 91 v-6 dakota only t-cover and serp pullys/brackets to get a serp system to bolt on to a LA engine like stock with stock parts.
the t-covers do fit and swap but they have to have the brackets figured out to run it.
looking over my mag heads and the LA heads I can confirm it will not use stock brackets from a mag engine on a LA engine with LA heads,
a LA pre-mag/magnum hybrid would do the trick.