stanza transmission question

I'm about to buy a 92 nissan stanza with automatic from a friend who had to
put another tranny in the car. He just put a transmission from the junkyard
in it, and it does fine except it seems to be starting off in second gear.
After it gets going it does fine. I think he even said that it'll kick
down to first once you get it up to speed and stomp down on the gas. I
searched on some parts sites and saw that there are a few parts that I
think could be causing this. My friend has been told that it is the speed
sensor causing this but I also saw some kind of torque converter sylenoid
and was wondering if that may be what is wrong. I don't know that much
about transmissions so any help would be greatly appreciated. Thanks

One more thing. The speedo doesn't work, not sure about the odometer. I
have been reading the forum and after reading, it now seems like it is
most likely the speedo head and not the speed sensor. I'll have my friend
remove the sensor and check voltage while spinning and look at the pinion
gear, then remove the speedo head and check the plugs. Would still
appreciate any input as I have not read many posts where people are having
probs with the tranny not going into first gear etc. Thanks again