I am looking for the GM part number for the 75-140 synthetic rear end oil. I do tow a heavy trailer do you think that is too heavy? I also want the use the 75-90 synthetic oil in the front.


Thanks

75W140 (http://www.gmdieseltech.com/store2/cart.php?target=product&action=view&product_id=162 02&category_id=262) 89021524


75W90 (http://www.gmdieseltech.com/store2/cart.php?target=product&action=view&product_id=161 84&category_id=262) 12378261

Thank You