Metr0Land is right that this is more a Forum question than a blog entry but you might try a Hornby tender drive unit from, for example, Peter's Spares. I'm not sure of the Fowler tender wheelbase but perhaps the X1494 unit would do the trick.  I've used similar units to power various models.

Not much you can do to make these units quieter. The Fowler tender drive, as fitted to the 4F and 2P, is in my experience not too bad in running qualities, and they certainly seem to respond well to DCC with a basic decoder. But no amount of lubrication seems to make them any less noisy - it's just a question of squeal or no squeal.

 

If you want to get rid of them, one option is to replace the mechanism with one of the custom tender drive units made by BullAnt:

 

http://motorbogies.com/index.php?main_page=product_info&products_id=90

 

I've got one of these and they are a very nicely engineered product.

Thanks gents, looks like I will have to buy chassis kits and convert to loco drive.