Did speedo gear units change on 240 tranny's after 1985?

After inspecting the bellies of a few 240s and 740s in the boneyard -
none have my speedo gear unit in the tranny. My 1985 245 has a speedo
cable running to the tranny where it plugs into the gearbox and the
tranny gears spin a little speedo gear that controls the dash gauge.

On my 1987 740, the rear differential has an electronic sensor instead
of this gear driven way.

I haven't even looked to see what tranny I have on the 1985 245
(automatic), but is my gear driven system something specific to a
particular transmission or date range? None of the other 240s and 740s
I've checked even have this.

Jamie

 

My '83 automatic has the speedo drive on the passenger (exhaust) side of
the tranny tailpiece.
btw, when the rear tranny mount rubber fails, the tranny bangs the
speedo drive on the mount and breaks the speedo drive off.

 

That might be why my speedo gear inside has a chewed up sprocket. It
still has enough to work correctly, but the seal has hardened and is
leaking. Bear of a part to find as a replacement. I'm still looking. I
think I saw one somewhere - but I forgot.

 

In '86 they changed to an electronic speedo just like the 700 series uses.