1973 1 ton trans question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

fourspeedwagon · 01-23-2015, 03:36 PM

I've got a '73 P-30 flatbed, it has a 350 and turbo 400. The trans is slipping and looses fluid-- Were there different variations of this trans to look for or avoid when shopping for a replacement?
thanks- Greg

**hatzie** · 01-23-2015, 05:42 PM

The TH400 trannies used in the '70s and '80s 30 series trucks are the "Short tail" TH400 with a fixed yoke rather than a slip yoke output. Meaning the output yoke is bolted onto the end of the internally threaded output shaft.
The TH400 from GM cars of the same era will have longer tail and a slip yoke on the output.

fourspeedwagon · 01-23-2015, 06:51 PM

Great Hatzie, thank you. That's just what I needed to know.

01-23-2015, 03:36 PM	#1
fourspeedwagon Registered User Join Date: Oct 2010 Location: Yakima Valley, Washington Posts: 576	1973 1 ton trans question I've got a '73 P-30 flatbed, it has a 350 and turbo 400. The trans is slipping and looses fluid-- Were there different variations of this trans to look for or avoid when shopping for a replacement? thanks- Greg

01-23-2015, 05:42 PM	#2
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,950	Re: 1973 1 ton trans question The TH400 trannies used in the '70s and '80s 30 series trucks are the "Short tail" TH400 with a fixed yoke rather than a slip yoke output. Meaning the output yoke is bolted onto the end of the internally threaded output shaft. The TH400 from GM cars of the same era will have longer tail and a slip yoke on the output. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

01-23-2015, 06:51 PM	#3
fourspeedwagon Registered User Join Date: Oct 2010 Location: Yakima Valley, Washington Posts: 576	Re: 1973 1 ton trans question Great Hatzie, thank you. That's just what I needed to know.



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