Hi I recently milkshaked my zf auto in my BF mk2 xr6t and Im going to go external trans cooler on my new zf but I've been told it can make the zf shift bad? Which is a good trans cooler to get? Don't want to spend the price of the pwr trans cooler what other options is their? Thanks in advance

Interesting question, I have a BA and after hearing of other having to rebuild trans due to coolant related disasters I went for a Kenco cooler bypassing the existing core coolant I noticed the shift is now smoother when hot, hot being one of two issues the other milky box when the cooler packs it in destroying the trans.

The PWR air/oil cooler is the best quality cooler you can buy for the money, it is not cheap for a good reason.
PWR make one specifically designed for the BF, i have had one installed in my BF11 Ghia with excellent results and no change in trans performance or shifting.
I have never experienced the Milkshake and never will.
There are numerous examples of successfull installations on the Ford Forums, taxi's in particular,
which speaks volumes.

Take a look here for lots of info: http://www.fordforums.com.au/showthread.php?t=11441275