So, it’s really not really a tag, which can make it a bit more difficult to identify if the transmission is really greasy. It is machined into the transmission in most cases. Identifying Turbo 400 By the Tag You’ll find the identification tag above the transmission pan on the drivers side. Where is the identification tag on a Turbo 400? The Turbo 350 has a basically square pan with one corner cut off. The Turbo 350 has a “kickdown” cable attached to the right side attached to a manual linkage on the transmission. Look at the driver’s side of the transmission. What’s the difference between a Turbo 350 and a Turbo 400? They are, for the most part, interchangeable on the same vehicles however, you would normally find the TH400 in larger engine applications because they are able to function more reliably at higher engine rpms. Turbo 400s use three tail shaft lengths the most preferred units for a GM swap would have the short 4-inch tail shaft. Reverse gear is 2.08:1 and third gear is an even 1 to 1. TH-400 transmissions are three-speed automatics, with a 2.48:1 first gear. How many gears does a 400 Turbo transmission have? The 700R4 has an overdrive gear (0.7:1), and a 3.06:1 first gear, but it’s not as strong. The TH400 is much stronger, but it doesn’t have overdrive and the first gear is only 2.48:1. For any rig it’s going to depend on the purpose.

Is a 700R4 better than a TH400?įor a daily driver on the highway a 700R4, for a mudder truck definitely the TH400. With ONE almost free modification and some minor valve body calibration changes, 800 HP on an otherwise stock TH400 is not a problem if it’s assembled well (good endplay, etc), and the 34 element sprag is a wise addition above 450 HP or any drag usage. How much HP can a TH400 handle?Ībout 400-450 HP/TQ is the limit on the stock TH400. A lot of people claim that he TH350 has less drivetrain loss than the TH400, which means that all things being equal, the TH350 is going to get more power to the rear wheels from an engine with equal power. The TH350 uses a mechanical kick down switch, whereas the TH400 uses an electric one.

Turbo 400 Transmission Serial Number