Your truck being an '83 probably has a TH350 trans. Probably will have to do little or no crossmember modification to mount a 4l60e/65e. Getting a 6l80e/90e probably wouldn't be worth it because you either have to have the matching PCM/bcm or buy an extra trans controller which is pricey. BTW, if you are considering a 4l80e, I recommend it.