Yep, I do, and yes, there is. I think I got the last NOS one from GM after it was discontinued (found on the locator) about 15 years ago. Takes a particular exhaust bolt for it, too, which I also have NOS (it may be available yet). I'll have to dig it out tomorrow and get you pics of them with the part numbers.
If you can't find one, I'll give you a sketch with dimensions if you want to fabricate one.
BTW, the car is my L48 Pace Car, power steering w/ A/C, TH350 -
Regards,
Steve