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I was wondering (more like hoping) if there is any external difference between a 27 and a 30 spline count 700R4 from a 1984 car? I want to step up to a higher stall converter from the stocker but I'm not sure which one I need to get. I really don't want to have to drop the tranny twice (once to count the splines and then again to actually swap the TC), nor do I want to buy both and have to return return one if at all possible. I didn't know if the stamped number could tell me anything or anything else. Thanks in advance!
Yes there is a number on the edge of the trans on the right rear corner. It will give you a clue as to what is is.
If it is an early '84 or '83 it is a 27 spline.
Cool, I didn't know that. Guess I should be ae to find out if the trans is likely original or not. I kinda hope it isn't as there are more 30 spline TCs out there. So if it's an '84 I have to find out the build date right? Where might that be located? Thanks again!
The transmission ID is on the passenger side of the oil pan-rail.
Shown below:
The last three numbers of the ID are the "Julian Date" (assembly date for the transmission itself), before the last letter (which will be: A, B, C, or H)
The1984 units were referred to as a "Change-Over/ Transition" model.
While there is no Exact Julian Date to signify which units have which Input-shaft, Stator-Support/ Oil-Pump, and Torque-Converter...
The "Late-1984" units are most likely to have the 30-Spline configuration.
Ideally look for a Julian Date of "275" or higher to have the best odds of having a 30-Spline unit.
OK I was able to get under the car and see it. It read 4YP034A so it's definitely a 1984 trans with a 3 digit code of 034. I'm guessing that it would likely be a 27 spline then? I hope not, I spoke with a friend who has a 2600 stall Yank TC that I could have but it's a 30 spline...
Take calipers or a micrometer and measure the diameter of the input shaft. If it measures .890" +/- .005" it is a 27 spline. If it measures .990" +/- .005" it is a 30 spline. This is the most accurate way of doing this, without guessing.
08-31-2020, 07:37 PM
