Bush hog identity? Help

I'm going to be needing parts for a trailer type bush hog. It is my dad's, but he doesn't know what brand it is either? We've had it since the early 70's, but it was used when my dad bought it. I just pulled the gear box off it today because I broke something inside. It was yellow in color, 5' deck. I'm going to need parts, so if anyone can tell me what it is, or if you have parts I would love to here from you. I have attached a picture also. You can e-mail me @ rboes@att.net Thanks.

Below I've listed, from my old notes, the companies that were helpful to me. You might try calling them...an hour on the phone might get you the company that built yours.

Wallace: very nice. Got their number of their web site.
Howse Implement company: 601-428-0841
Agco parts division, 800-767-3221
World Agri Tech, 800-368-5831 Darrell Harp Enterprises, 256-356-4424

Good luck!
Tom