46RH overdrive ratio.

Headintheclouds said
Thank you for that. Sorry if my lack of understanding is frustrating but I'm finding it hard to work this out.
Please try to be patient.

It's all good, I was misunderstanding what you were trying to get at, I thought you were stuck on the 0.69 vs 0.68 not converter slippage %'s.

Headintheclouds said
Amongst other things I'm trying to work out the speeds to switch in overdrive and lockup automatically.

I'd start a new thread asking just this.

Headintheclouds said
In the above example it looks as though switching in overdrive without lockup introduces a load more slip that would generate loads of heat in the transmission fluid and harm gas mileage.

I'd leave out this just makes confusion of the question

Headintheclouds said
This leads to questions about stall speed and slippage below that speed - and I got some very sarcastic answers when I last asked about that. it's pretty frustrating as we all have to start somewhere. My area of expertise is electrical systems. I have seen what seem to be some very dumb questions asked on forums that I have answered patiently and I think I have really helped people.

Ask away that's what the forum is for, try not to let some frustrated you from posting.