Can an 4L60E bolt to an 1981 Chevy 350?

It will bolt up but it will not work because it is an electronic controlled transmission. That's what the E stands for. The 81 model does not have the computer system are even the wireing harness plus MANY more things that the 4L60E MUST HAVE to work correctly. You need a good 350 or 400 turbo transmission to put in that truck.