the valley pan replacement is a $1200 job at the dealer. you should replace all the coolant hoses back there at the same time. it should cost you a couple hundred more.

the intake has to be removed it's a big PITA (time consuming). it take about 8 hours.

it's easy to see if it's leaking. it'll drip down by the transmission if you park uphill. another place to check for moisture on top of the intake where it meets the valve cover. I don't have any pictures.

mines been leaking (very slowly) for a while. trying to decide whether I should do it myself. it's such a pain to reach back there at the rear coolant log to R/R all the parts.