When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Nightpager, a company in Japan sells brackets that allow LS400 calipers(which are actually the TRD IS300 BBK) to bolt up to GS300. The bracket is actually an RCA that allows part of the GS suspension to clear the LS400 caliper.
RCA won't help. The physical hole sizes are different.