Last weekend I punctured a big hole in my gray and one of my water tanks on my SLC3905. I was wondering if anyone has ever replace.....Im wondering how difficult. Local rv place want about 500 just for labor.....

I haven't replaced mine but I did have to drop it to install a winch (07 LE3505). It would be very simple to replace my tanks and I would imagine yours would be almost the same as mine. $500 in labor is way too much IMO.

ill second that. i sprung a small leak in my grey tank so i dropped it and brought it back to the manufacturer. they said they can try and fix it for 20 bucks or i can buy a new one for 240 bucks. i spent the 20 and re-installed it after welding better supports and such. i am now getting ready to spend the $240 as the repair didnt hold. anyhow, the removal and install was very easy on my forest river 38' 5th wheel. not sure which trailer you have but i imagine they are similar. basically you need to disconnect (and mark) the wires going to the sending units, unbolt the support straps/angle iron, and let her drop down. the abs pipe that enters the tank is basically sealed with a rubber seal and some plumbers dope. when re-installing just coat the end of the abs pipe with some plumbers dope or? and slide it ride back up, bolt in the braces, and re-connect the wires. its a simple deal. or you can have me do it for 5 dollars less than the RV place..ok just funnin. but you get the idea.

What he said!