While taking my engine apart, I had a lifter that put up a fight and ended up a little marked up towards the top. Can I replace 1 lifter or am I gong to need to replace all of them?

 

You can replace just 1.

 

Assuming you put them back where they were if the engine was ran, and they have no excessive wear.

 

if that lifter is marked up from trying to remove it i would take a hard look at the bottom of that lifter.if 15 came right out and one was difficult there could be some wear at the bottom of the one that came out hard.if that's the case there has to be damage to that cam lobe

 

This is possible, but more likely is varnish build up on the exposed end of the lifter. Next time, use the correct lifter extraction tool to avoid damage.

 

Does the bottom of the lifter show wear, it will look concave. If so then you need to inspect all the others and the cam lobes.

 

only varnish on one lifter? not likely