ok i have a 2001 zr2 blazer that has a 1870 slip code so i am going to replace it but when i call around to all junkyard they tell me that 2001 blazer is special year and i can only use a 2001 trans . does anyone know why this is

 

P1870 - Transmission Component Slipping

There are some repairs that can be made to your transmission for less $$ than replacing it.

And they are feeding you a line of bull. You should be looking for a 2001+ 4L60E transmission from any vehicle so equiped. The only difference you have to look out for is that some pickup trucks came with a larger, 300mm torque converter.