well, i am new to powerstroke fourm but my dad had 2 old 7.3s and a f650 and now recently has a ford v-10

and a mack granate. well my neighbor has a conctuction and drilling buisness and so dose my dad.... well they work together and my neighbor bob had a f-350 7.3l 2000. it has a servace bed on it and he wants to trade it to my dad for his 12t tag along trailer(5000$) it has 135000 miles and has new oil, injectors,turbo,i guess pistons or rings on it and berings in some things. it was all gone over before put out to sit.(neighbor has new sevace bed f-250. i was wondering if it is a good deal, what to look for and anything about the 7.3l i have no clue except they sound cool!!!
please help me i am clueless