I have a Jet lathe,best buy I ever made,probably a bit out of you range though,as its a 3520B,from what I see online(write ups etc;) the 1642 is a good mid range lathe,but the lathes you have none of the accessories will fit the jet,so it will be new backplates/inserts for your chucks etc;,but their both 2MT the same as the jet so those accessories will fit,swings and roundabouts though whenever you buy a new lathe,cheers,
Eric.