If vehicle type is not known check the S2 solenoid. A domed top on the S2 is a GM. A flat top with four ribs radiating from the hole in the center of the S2 is a Nissan/Volvo. Nissan, Infiniti & Volvo use one shift solenoid configuration. Others use a different configuration.
Look for a letter that is cast into the valve body to the right of the S4 solenoid hold down bolt.
"No Letter/Blank Space" and valve bodies cast with a letter "A" are considered early.
Valve bodies cast with a letter "B" or "C" are considered late.
The red arrow indicates the casting location.
Check for B5 Spring
In model years '05-later, all Nissan and most GM/Volvo valve bodies may have a spring under the B5 control valve. It is very important to check the 10th digit of the VIN to verify production year. If the 10th digit of the VIN is 5 or higher, check your original valve body for a B5 control valve spring as shown. CAUTION: The wrong valve body will cause shift quality concerns.
Remove the 2-bolt end plate and check under the B5 control valve to see if there is a spring.
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