DS12211 Billet Steel 429 Flexplate (Multi-Pattern)

Billet Steel Flex Plate Multi-pattern

This flex plate fits ’64-’67 Cadillac 429 engines with the TH400 or other modern transmission bolted directly to the block (or using an aftermarket transmission adapter), with the starter bolted directly to the block.
This will not work with ’64-’65 Cadillac 429 engines that have a hydramatic transmission, or a TH400 bolted up with a factory cast iron adapter, and the starter bolted to the transmission or adapter. For these engines with a factory adapter and a TH400 (or an aftermarket adapter stacked with a factory adapter to mount another modern transmission), use flexplate DS12213. For engines that originally had a Hydramatic transmission bolted directly to the block, you can adapt a modern transmission using adapter DS31301, which comes with it’s own flexplate. We do not offer a replacement flex plate for the Hydramatic transmission.

Transmission identification – the Hydramatic is a 4 speed transmission, with a shift pattern of PND21R. ‘Modern’ transmissions have a shift pattern of PRND21, PRNDL, PRND321, etc.).
Adapter identification: Aftermarket adapters are generally made of steel, machined not cast, and essentially flat on both sides. With the exception of the DS31301, they should be roughly 5/16″ thick. Factory adapters and the DS31301 are quite a bit thicker, and include a starter mounting provision. The factory adapter is cast iron, and is not solid – there are large hollow areas in it.

When hooking up a 429 Caddy to a Chevy or GMC converter, you have to keep in mind that the bolt pattern on the converter must match the hole pattern on the flexplate. TH-400, 4L80E, and Allison converters generally have the “large” diameter pattern (11.5″), but light duty trannies (‘Glides, TH-350, 700R4, and TH200) have a smaller pattern (10.75″). You cannot safely drill out the stock flexplate, because the smaller circle falls on the stress ridge on the Cad flexplate. Three holes in there, and your chances of blowing the middle out of the flex plate are pretty good.

All of our aftermarket and OE replacement flex plates and flywheels have a Cadillac 166 tooth ring gear for use with a stock Cadillac style starter. This flexplate is zero balanced like stock and compatible with some ’64 and most ’65-’67 429 Cadillac engines using the DS31201 or DS31203 mounted directly to the block (no factory adapter in between), and the starter bolted to the block.