I refinished an old Lund a few years back and had good luck using “aircraft stripper” It is a paint remover that you can buy at an autobody supply shop, It worked VERY well, took off 3 coats of paint realeasy, just be sure you have good ventilation and read all instructions. I then bought paint from a lund dealer along with a self etching primer and had a body shop spray the paint(they charged me $100 in 1990) for me. it turned out like a factory finish! Good luck!