[midniteblues]

I would get the whole system.
If the headers don't work out for many reasons just install the exhaust and get down pipes made too fit with the manifolds.

All square body trucks had leaf Springs if you have coils you could run into fitment issues going over the axle and center c member.

If your truck is auto you should be able too use the headers.
If it's manual be sure the last Dr side tube goes straight down too clear the z bar and linkage.

Other concerning issues with headers are lwp ps and ac brackets. Spark plug wire fitment. Fitting around the motor mounts since squares had different mounts and some just hang way too low.