Transmission Cooler Leaking - Engine Temp lower than normal

[NMMalibuFamily]

So, the transmission cooler started leaking today. I guess a replacement is needed. The odd thing is that the engine temp stayed pretty low today - around 110 degrees. Three. questions:

 

1) is the transmission cooler pretty universal?  Bakes has two online - a 5” and 9”  

2)  is the cooler easy to replace?

3)  any idea why the engine would be running cooler than normal?

[tvano]

easy to replace BUT don't over-torque the fluid lines that lead to the transmission and don't over do it w tightening the water hoses lest you crush that soft-ish brass cooler.

[Teleman]

I would say you also need a new thermostat too. The OEM one tends to suck. I got a cheap NAPA one and it seems reliable now for years.