99 Honda Passport, reverse only working

I have a 99 Honda Passport, 2wd, AT. Transmission has no forward gears, only reverse. No trouble codes. Took it to a transmission shop, they supposedly checked the electronics and said it was internal to the transmission. Purchased a used transmission from a salvage yard and had it installed (not at the same transmission shop). The "new" transmission acts the same as the original, no forward gears, only reverse, no trouble codes. Not sure if it is just a coincidence, or if something else is the problem. Any ideas?

Check your voltage output on your alternator WHILE under load, i.e. heater/radio ON and truck running.

More times then not, good trannies are changed out for reason no other then a failing alternator....sad, but true, it's VERY common.