Top end so probably Wedge, they did use a roller for the front mech (though on other side normally I think)
Roll-Ahead forks....
Though wishbone is the odd one.
as 1990 Wedge went for the wonderful Elavated & Twin downtube.
Wedges and Blizzard Slopes had fastback says from all the ones I've seen.
Possibly a Custom (T-Bolt/Wedge) build then
Avalanche was Toyo built so had Toyo style rear stay fixings.