Need help Identifying this transmission.

[YBNORML]

A couple of years ago I took this transmission out of an Astro van. I do not believe that it was the original transmission. The van was heavily modified with a V-8 conversion. The transmission was "supposedly" re-built with corvette internals. I am not sure whether or not that is true, however I did get the chance to drive the van before taking it apart and the trans worked well.

Can anyone help me narrow down the year of production and provide any other details on the tranny?
I'll post some better pics tomorrow.

The plan is to install it in my Blazer behind an early 80's 350. I Found this link http://transmissioncenter.net/700R4_Swap_Info.htm. The install seems pretty simple. I have never dealt with this style of transmission before, what is the plug with the three wires for? I think it is for the T.C. Lock-up. What is the Lock-up for and do I need it?

Anyways here are some pics I took of the transmission, plus one of the Blazer it's going into