Looks like I've got to drop the gas tank on my '70 to replace the fuel gauge sending unit. Before I begin, will I need any parts other than the sending unit itself? My '56 Bel Air had a "donut" that served as a seal between the tank and the filler neck. Is the neck separate on a '70? If so, is there a "donut?" Anything I should watch out for?

One more thing...there appear to be aftermarket and GM sending units available, with the GM costing qute a bit more. Are thet worth the extra money?

Thanks.

The filler neck is solid, Tim. Drop it a few inches to make it easier to disconnect some of the rubber lines on top. Keep your fingers crossed that there may be a build sheet up on top. As for the sender, I have not used the aftermarket unit so I cant say. You get what you pay for may or may not apply.

Spend the extra money and get the G.M. sending unit.

You WILL be ahead time and money. I bought the last G.M. sending unit available in the country for my 83. Cost $160.00 and I feel more confident that an O.E. will outlast and out peform an aftermarket.

Only donut/o-ring that you should really need, is the one that goes on the sending unit and it should be supplied with the new sending unit.

Hardest part of replacing this unit is the removal of the fuel tank itself.

You may or may not need some new fuel line hose to connect between the Tank and fuel line. Remember its 38 years old, and could be quite weathered, cracked, hard or brittle. If it were me, I'd replace it any way with new while I was there. Two foot of it would be pleanty to get, and don't for get new mini hose clamps for it, as the originals will most likey be band clamps and have to be cut off. If the aftermarket gauge assembly is AC Delco, you won't have an issue with it.
http://i300.photobucket.com/albums/nn18/coyoteon2/AMW-bc-front-Larry.jpg

Thank you!!

Before I start to drop any fuel tank I always spray the tank strap bolts down with JB 80 (Justice Brothers) penetrant! Rust, undercoating, gravel spray etc. really can be hard on the threads. The straps will twist & snap much easier than a regular bolt and if you don't have new straps on hand, it can really put a halt to that Saturday afternoon job!

Once again...Thank you.

Don't forget the lock ring. It comes with a new tank but not the sending unit. Mine was rusted to the point of no return.

Tim, Good advice above and I would add that if you had not planned on it already, to throughly clean out the inside and paint the outside of tank while you have it out and accessable. A quart of degreaser and a parts cleaning brush will be good to use before you remove the old sending unit. I did this recently on my 87. I also purchased a quart of Pre ( removes tar,grease etc. ) before final painting. I then used Tank Tone which is a zinc based paint in spray can available from www.eastwood.com or auto supply stores. It gives a nice brushed aluminum color to the tank and is better than just regular spray can paint which would not be good around gasoline. I then painted the two straps black to stand out. I saw 82Elcos tank and he had his done in a nice gloss black power coating. Compare the sending units side by side before installing so you may not have to drop the tank again as I did because they sent me the wrong sender and they look very similiar. I don`t know how your lines run on top of the tank and bed frame compared to my 87, but be sure the rubber lines are not pinched as there is very little room there. Hope this helps.

Don't make the mistake I did and put to much pressure on the neck by resting it in an awkward position on the way out. I left too much fuel in it and it was heavy. There's a lot of leverage there and the neck is just soldered to the tank. Mine cracked at the joint and I was lucky enough to find a good radiator guy to fix it. You may want to get the seal kit from Eastwood. It cleans out then coats the tank with a gas proof sealant on the inside.