I've never actually seen OP's truck; thus cannot Know exactly what's going on under his hood; with his 6 box.
Most things have their place; I'm quite famliar with MSD 6-series analog CD ignition boxes and with their use in Oval Track racing. As well as their failure rate. I've personally owned several such 6 boxes. And I also Know how to read and follow MSD published wiring diagrams; I've seen plenty hacked-crap ignition systems.
I'm also rather familiar with OE L31 ignition system & EFI as found on OP's 1999 5.7L (L31). I own a couple of those OE systems as well.
From my experiences, the OE L31 ignition & EFI system has No need for a 6A; and that 6A would be of No benefit to a properly functioning OE L31 ignition / EFI.
OTOH, but in this very instance, a 6A is a liability; a failure waiting to happen.
If and when a Daily Driver's ignition system fails (one that's dependant upon a 6 box); it's likely that No one nearby will be able to diagnose or repair it anytime soon.
Hopefully, OP's 6 box is just "for show" and isn't wired into his rather good OE L31 ignition system.
Most things have their place; I'm quite famliar with MSD 6-series analog CD ignition boxes and with their use in Oval Track racing. As well as their failure rate. I've personally owned several such 6 boxes. And I also Know how to read and follow MSD published wiring diagrams; I've seen plenty hacked-crap ignition systems.
I'm also rather familiar with OE L31 ignition system & EFI as found on OP's 1999 5.7L (L31). I own a couple of those OE systems as well.
From my experiences, the OE L31 ignition & EFI system has No need for a 6A; and that 6A would be of No benefit to a properly functioning OE L31 ignition / EFI.
OTOH, but in this very instance, a 6A is a liability; a failure waiting to happen.
If and when a Daily Driver's ignition system fails (one that's dependant upon a 6 box); it's likely that No one nearby will be able to diagnose or repair it anytime soon.
Hopefully, OP's 6 box is just "for show" and isn't wired into his rather good OE L31 ignition system.