FOUND IT! I knew I'd seen it somewhere...
Autofab 2WD GM frame brace-- 1973-87/91 GM's
"The above kit was designed to satisfy requests from Chevy 2WD truck owners who know 4WD owners or used to be one. They wanted some insurance for their frames as well. This kit mounts on the front side of the crossmember and reinforces 2 of the steering box mounting bolts. Fits 1/2 - 3/4 - 1 ton trucks. It's not as common a problem with 2WD trucks, but, we have had to repair them as well. For a small price and a little work you will have peace of mind.
All steering box gusset kits are $105. you can order by calling us direct at AUTOFAB (619)-562-1740 or by sending an e-mail to john@autofab.com with your name, address, phone number and your order or questions."
Installation article
http://www.4wheeloffroad.com/howto/3099/
Manufacturer home page
http://www.autofab.com/