Discounting my previously snarky comment (injecting some humor only), you need to ascertain the bed length of your present TC. Is it for an 8 foot bed or a 6 foot bed? An 8 foot camper will fit in a 6.5 foot bed but will hang out the back quite a bit and my put the Cg in back of the rear axle which may impact steering and handling.
Another aspect to consider is, new truck manufacturers are changing things like tailgate width (openings) and cab height (higher) so your old unit may not even go in a new truck (depending on what you buy or the cab over may not clear the cab roof without some modification (spacer) in the bed. I'd take measurements of your old unit and have them along when shopping for a new truck.