wheel questions

[micus]

hey guys i had a few questions about my truck,

its a 67 gmc short fleet, and i was wondering about wheels, im looking to order a new set of wheels for the truck, but im not sure about bolt pattern and backspacing, there are 6 bolts but im not sure if their are variations of the 6 bolt pattern, the one i most commonly see is 6x 5.5 but im not sure if that is what i have, and then theres back spacing, im only looking to get 17's so i dont think they will be a problem when i lower it, 4/6 , i want some wider tires in the back and just normal in the front, what type of backspacing should i be looking at?


so does anyone here kno what my truck is through their own experience? thats what im hoping, sorry for all the questions, you guys probably get them alot, im dangerously new to this,



thanks in advance