You can, but you'd better know exactly where they go. Mine were put on first, but I had to take them off when the wood went in because they just didn't line up quite right.
Good luck.
1948 Chevy 1/2-Ton "Tuesdays with Morris" In the Legacy Gallery Find it - Fix it - Drive it
Here are some instructions we have for installing bed strips. Yours is a 1 ton and these are for short/long step, so the dimensions may not be exact, but this should help. http://www.mar-k.com/37-53anglestrips.pdf