Sam's Bolens has an aftermarket 3pth set up for your HT20, ($$$ !) . There has been some talk that Ballard Fabrication may be coming out with one. They offer the earlier LF style which won't work on your 20. Keep your eyes peeled on Ebay for one. Contact Rick Show (site sponsor here) 'BlackJackJake' he has a knack for finding these ,he's found me 2 or 3 .