1968 250 camper special newbie/tie downs

I bought my truck to pull a vintage trailer (canned ham) that's been in the family since 1969. I had difficulty going from an SUV to a truck in regards to backing the trailer (which turns on a dime). I realized it was time to pass the trailer to the next generation. I still needed something to camp in and decided on a slide in camper.
Found a 1975 Chinook in good condition. I want Torklift tie downs that mount to the frame, but they only have go back to 1973. Anything before that is "custom". Which translates to $$$. Does anyone know if the frame for a 68' is that much different than a 73'? If they are the same or similar, hopefully just a modification could be done?









