long bed dimension question

[Bladeboy1998]

I am looking into getting a 67-72 truck and I am wonderingwhat the exact bed dimensions are. How long is the 8 ft box, how wide is it tk the inside of the bed rails and how tall ate the wheel wells? I want to put my john deere gator 625i in the bed and it won't fit in my 03 chevy 2500hd 8 ft bed, it won't go past the tail lights. I was thinking of lifting the gator in with a chain fall. Sorry for being so long winded 😊 if this doesn't make sense let me know ☺thank you guys