73 c10 hitch on a 68 c10

[dmsteele92831]

Ok, so I read somewhere on one of the postings that you can use a 73 and up hitch on a 67-72 truck (I have a long bed). I can't remember which posting it was from but a guy said you would have to drill holes and make spacers (or buy them at Home Depot to compensate for a 1/2" lower. There was a guy off Craigs list that had a hitch off a 73 so I drove my truck over and made sure I everything would line up. I figured I could make it work with drilling holes and making/buying spacers. I sanded it down and painted it just for good measure then used the existing holes on the hitch and drilled new ones into my frame. Now my question is... since I have spacers in there should I be fine with just two bolts per side? I tightened them down quite a bit and used threadlocker as well just to be safe but I want to make sure there's not a chance of a bolt shearing off. I used 1/2"X2" bolts from Home Depot (not sure what grade they are, but they're used for construction so they should be strong). Attached are pics. Let me know what you think and let me know if I should drill holes in the middle of the bolts that are in place now and add another bolt/spacers to each side. I will be pulling a 19' trailer max.