2000 trans slipping and speedo gone haywire

[blkmonday]

I have a 2000 s10 with 135k 4x4 6cyl extended cap. Truck was sitting for about a year. Decided to get her going again. New tires front end work and a few emissions things to pass emissions. Truck runs pretty decent. This morning the trans started skipping. Check fluid and it was low a quart. Haven't noticed it leaking but it's possible. Truck is better after the fluid but after a longer test ride it's skipping still. Had to manual shift it a few times to get it home. Not sure if it's related but speedometer is jumping all over the place when it's skipping. Is there a modulator valve or something it could be or is my transmission toast? Anything to check before it goes to a shop or for sale as is?

[blkmonday]

Vehicle speed sensor? Lots of internet searching and it seems this is a possibility and explains why speedo is going haywire as well. For 13 bucks I ordered a cheapo one off Amazon fingers crossed because if it's the trans this thing is for sale.

[Blue Bowtie]

Usually when a VSS fails the PCM will transfer to the default lookup tables for shift control, causing a higher line pressure and firmer shifts, not slippery shifts.

It is possible that since the speedometer is erratic when the condition occurs, there might be an electrical connection failing, causing both symptoms.