it is advisable to replace both batteries at the same time. a weak one will drag down a good one. and you have two marginal batteries again. powerstrokehelp.com youtube videos are great. guy is like a powerstroke god.
some of his old videos are kind of crude quality but he gets the point across.
powerstrokes need two good batteries to start. in cold . when I first bought my ambo it also would not start below 30 without block heater, found out battery under hood was to small and one on right frame rail wasn't hooked up!. so I had been trying to start it and sometimes having luck with one...
912 /921 style automotive bulb will work I got cheap ones from amazon for my low domes. and left the high in
the cheap ones I got from amazon started flickering tho sometimes after couple months. mainly when van is shut off and voltage is below 12.2ish
mine did that also. try a long screw driver on the pulley you should be able to hear it.
also does it have two pulleys right next together? I think I paid around 75 bucks for the tensioner with both pulleys.
when I ended up getting the tensioner on which is pretty easy the belt was so...