If it is a 1st gen then it will not have a nv4500 unless someone put one there, 1st gens have a getrag360 which is also a 5spd OD. AFAIK 1st gen dodge does not have a cut trans tunnel but You can cut it and make it that way.
The 89 are easier to work on, first see if the gear at the trans tail housing is set properly, You can also pull it (the top) and turn it with a drill then You can tell if it sending a signal at all. If that is ok then You can pull the dash cluster and carefully pull the speedo when You look inside there should be two plastic gears inside that like to break in pieces, if so You can order replacement gears here
http://www.speedometergears.com/chrysler-odometer-gears, hopefully that is all it is.
Was th KDP tabbed or fixed? Make sure You do if it was not done. Here is a pic from one of mine
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