I recently purchased a new Class III receiver hitch from LMC (Long Motor Corporation) in Lenexa, KS. Their website is
www.LMCtruck.com. This was a bolt-on accessory, however I did have to drill 4 1/2" holes in the bottom flange of the rear frame rail. There was minimal interference with the factory bumper brackets.
My memory tells me it cost $129.00. I live in Lenexa, KS so I was able to pick it up, saving me the shipping costs. I am pleased with the quality of the product, the fit and finish and the ease of installation.
Best of luck. You might also try
www.chevyduty.com for this and many other cool items. FYI-I'm not endorsing either of these companies. They are both located close to my house, so I get a lot of parts for my '66, C-10 and '66, K-10.