I'm asking this question for a buddy who's building a '49:

What is the best late-model factory seat to use in a 48-54 truck? He would prefer a 60/40 style with an armrest, if possible.

I had thought about using a 60/40 from an 88-98 :chevy:truck but decided to go for the more stock look. This seat looks factory, but has a few options.
http://www.glideengineering.com/products.htm
They list a bench and a split bucket.

i used a seat out of a late 80s early 90s cutlass car.