Advance Adapters is great for adapting SBC or BBC to different types of transmissions. they also make adapters, but for all purposes they do not make adapters to sandwhich a 38 sedan transmission to a 54 chevy truck bellhousing. In fact they don't really offer any adapters that would fit the bellhousing of an Advance Design or Task Force truck bellhousing. I put a NV4500 behind an AA adapter plate on my 59 gmc. I had to machine it down to index properly to the bellhousing. the chevy bellhousing adapters they sell are indexed to the 68 and later bellhousing pattern with the bearing retainers that are 5.125 inches in diameter. The 48-67 bellhousings were indexed at 4.686 inches. what this means is that the adapter plate they sell will not fit inside the older bellhousing unless you do 1 of 2 things... bore out the bellhousing, or turn down the adapter plate. Still apples and oranges for the 1947 and earlier bellhousings.