401-425 to TH400

[Rob56Century]

Hi, I'm new to this site, but the bit I've seen looks good. I have 56 Century, thinking of dropping in 401-425, and would like to use TH400 instead of original 56 tranny. Searching wrecking yards today, found LeSabre('65?) with small black, BOP pattern TH400 variable pitch, then found 65-66 Wildcat with 401-425 (pieces missing) with strange round top bell housing tranny, NOT BOP pattern. What gives? I thought Buick used TH400 from '64 on. Also, how can I tell if this is 401 or 425. Thanks, Rob

[Dr. Frankenbuick]

Rob,

The 65 LeSabre had a 300 engine with either a ST 300 or ST 400 transmission in the BOP pattern. The Wildcat had a a 401 or 425 with an ST 400 in the Nailhead bolt pattern. These were made in the Nailhead bolt pattern from 64-66 with 65-66 having variable pitch converters. The ST 400 was the predecessor to the TH 400 that began in 68. Many of the parts interchange between the ST 400 and TH 400, and a ST 400 can be easily converted to a TH 400.

[Rob56Century]

Allright!! Thank you for explaining that for me. and I searched around the site and found out how to ID the engine, so I'm good to go. I like this site Rob

[tp57ranchero]

Also look at the 65-66 rivieras they have what you want. I just purchased a 65 401 with a T-400 s/p tranny to put in my 59. You will have to convert it to an open driveline though. TP