Oil pan change?

a few Q's for ya all,First i need to change my pan gasket leaks like crazy,the hard part with that is that i need to change it in the car(72 dart 318) is this hard to do it dosent look bad but looks can be otherwise.second Q i was looking into changeing pan when the motor was out but the wallet said no an would it be to much to change out pan in the car too heres the pan im looking at http://store.summitracing.com/partdetail.asp?autofilter=1&part=MIL%2D31935&N=700+400380+4294908110+4294862852+115&autoview=sku let me kow what u guys think an whats the best way to do all this i dont want to pull the motor but if thats what i have to do then thats what ill do!thanks MIKEY