Topic: 403 and 400 trans swap

[1980tafinally]

Hello,

I was wondering will a 403 olds and a 400 trans be able to just mount right into a 1980 trans am because it did not come with the option for that year or will I have to make holes for the motor mounts?

[NWW-79 T/A]

.

[eroc022]

Yes, it will bolt right in. Th350 anyways, th400 requires a different transmission crossmember and driveshaft, Oldsmobile powered cars never got a th400 or 4spd manual

[1980tafinally]

Thank you. I thought I read somewhere that it was an option to get the th400 with the 403 olds.

[Grand73Am]

No. The last year for the th400 transmission in a Firebird/TA was 1974. So, from 1975 on, there were no factory installed th400's in any Firebird or TA. 

[1980tafinally]

Would i have to change the bell housing?

[Grand73Am]

No if you're using a pontiac or olds. The pontiac and olds have the same bellhousing pattern. The Chevy is different.

[eroc022]

And Buick !

[oldskoolubr]

Hey Eroc the I thought the crossmember for the 350 and 400 were the same just different mounting location?

[eroc022]

Crossmembers are different, you can make the th350 work by redrilling holes, but the th400 crossmember sat differently on the frame

[oldskoolubr]

Oh Ok I thought you just moved the Crossmember back to different holes?  Was going to make that swap but ended up getting a good deal on a TH350 with Stall.  Thx Sorry for the Temporary hijack!