Chosen Solution
Transmission change from 700r4 1988 to 4L80-E tranny in 1998 chevy. Both have overdrive and 8 foot beds.
Hey Jeff. If I remember correctly, the 700r4 is the same internally as the 4L60-E. The 4L80 will have a different gear ratio and is a different size (regardless of bed length). The main problem is that the E stands for electronically controlled, which will be your biggest issue. It’s been a long time since I did a 4L60 swap but I think you also have to replace the 40 tooth reluctor ring for your Vehicle Speed Sensor to please your ECM, and the torque converter bolt pattern is different, so you’ll need a different flex plate as well. It would be a complicated process, but I hope this will point you in the right direction.
