It's fits a 4L60E. In '90, the 700R4 was renamed the 4L60. In '93 GM started using electronically controlled 4L60s and named this version 4L60E ( E for electronic ). The 4L60/700R4 used a mechanical governor, that was driven by a helical gear cut in the center of the output shaft. There was no need for the governor in the electronic shift control model, so the helical gear was not machined, but the rest of the output shaft remained the same ( including the rear yoke splines ). In the second link, the picture shows ( top to bottom ) the output shaft for a 4L60E, 4L60/700R4, 4L60E 4 wheel drive and then 4l60/700R4 2 wheel drive. In 2001, heavy duty improvements were made to the 4L60E, which included stronger planetary gears and output shaft. This is when the longer splines showed up.

Output shaft for '98 and newer GM 4L60E/65E/70E 2 wheel drive transmission.

References:

https://www.ebay.com/itm/4L60E-Extension-Tail-Housing-Output-Shaft-6-Bolt-4L6...

Reason:
Same problem I was having but if you look at my 2nd pic you can see that the "space" is much longer before you get to the bottom of the splines, and they aren't as long as the 4L60/65/70E shafts.

It's fits a 4L60E. In '90, the 700R4 was renamed the 4L60. In '93 GM started using electronically controlled 4L60s and named this version 4L60E ( E for electronic ). The 4L60/700R4 used a mechanical governor, that was driven by a helical gear cut in the center of the output shaft. There was no need for the governor in the electronic shift control model, so the helical gear was not machined, but the rest of the output shaft remained the same ( including the rear yoke splines ). In the second link, the picture shows ( top to bottom ) the output shaft for a 4L60E, 4L60/700R4, 4L60E 4 wheel drive and then 4l60/700R4 2 wheel drive. In 2001, heavy duty improvements were made to the 4L60E, which included stronger planetary gears and output shaft. This is when the longer splines showed up.

References:

https://www.ebay.com/itm/164672892434

https://storage.googleapis.com/advanceadapters-com/images/cms/sized/700R4L60_...

https://www.novak-adapt.com/knowledge/transmissions/automatic/th700r4

https://www.novak-adapt.com/knowledge/transmissions/automatic/4l60e/