A commonly asked question on our Tech Line is, "How do you know what ratio Powerglide I have?".  The answer is easy if the unit is disassembled, the planetary is sitting in front of you and the unit is stock General Motors parts.  The cast steel housing with non-removable pins is a 1.76 ratio.  The stamped steel housing with removable pins (remove three screws) is a 1.82 ratio.  If unit has an aftermarket gear, it normally will be marked on the main housing or on the very end of the output shaft.
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• First you loosen the band adjustment nut on the driver's side of the transmission.  Now while holding the nut turn the adjustment bolt with a 7/32" hex key wrench clockwise till it is tight.

• Second you mark the input shaft and the output shaft at 12 o'clock with a piece of chalk or crayon. 

• Third turn the input shaft till the mark on the output shaft makes one complete revolution.  The mark on the input shaft should have made 1 3/4 turns and be pointing to 9 o'clock if it is a 1.76 ratio.  If the mark on the input shaft turns 1 13/16 turns and is pointing towards 10 o'clock, it would be a 1.82 ratio.

Note: This procedure can be used to check aftermarket ratios, but you will have to figure out the clock position for each one.  Some of them are almost the same, Example: 1.89 and 1.90.

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Turbo Action Technical Tip #4