http://amalgamatedti.com/lower.pdf Seems like they do, but I don't see any place to place an order. None of their products have a way to order, but everything has prices. I dunno...........
Well I think I found a new contender for a 308 build. http://axtsweapons.com/products/AX762
Great looking stuff but lots of money for their stripped 556 lower though. About the highest Ive seen.
Yes they are VERY spendy. I do think it's the best full ambi lower on the market though. I haven't SBR'd a lower yet, but the AX556 will get the nod when I do.
FWIW, I think you get the best results with a thoughtfully designed custom AR. About the only factory AR I still have interest in is the KAC SR-15 E3.