Did you index the speedo pinion correctly when you installed it Mick? Each pinion has a certain number of teeth. And there are 3 indexing points on the tailshaft of a torqueflite for speedo pinions of different teeth counts. For example if your pinion has only 24 teeth and you just stuck it in the hole in any position it may be in the position for a 48 tooth pinion so to make it work it would just need to be rotated to the correct position so the pinion teeth engage into the teeth on the output shaft.
You may have to remove the pinion and count the teeth and clean any grime off the output housing around where the pinion goes in and look for the teeth counts to know where to stick it in.
BTW: On the housing the numbers are stamped in ranges of teeth counts such as 20-30t, 30-40t, 40-50t. So if your pinion is a 24 tooth it would go in the first set. Also I'm just going by memory on those numbers so they probably won't be exactly the same numbers as I said but you get the drift.
