Honestly, I wouldn't waste any money on a TTB lift.. its just throwing good money after bad.. A SAS is really no harder than a ttb lift, and cheaper too..
Going rate on a 79' dana 44 is about $100, or less....
Move the factory radius arm brackets back to where the cab mounts are, weld on a track bar mount.. and bolt it in... it's really that easy..
Oh yeah, a set of used 4" 70's coils to clear the crossmember, and a 85-97 F-350 draglink... it all bolts right in..
These trucks drive/handle/wheel so much better with a solid axle its not even funny..