+1 on ASC. Take an axle apart so that you know what to order, like square or round axle, 1" or 1 ⅛". You can get discs made in Brazil or India.....difference is amount of Iron I think, one is 7 units of whatever and the other 8 units as I recall....never noticed the difference operationally.
The 3mm blades are the thinnest and cut the best for smaller discs, like 6-8'. But if you are in rocks you will want to get the thicker blades to reduce any breakage.....never broke an ASC disc in heavy clay, few rocks and those are 3" range, and I load mine up with as much weight as I can stack on them....like currently I have about 500# on top of a 6' I extended to 7' with ASC parts. I do drop as slow as is convenient for what I am doing on hard surfaces. If the field has been plowed and fairly soft, I drop her fast on short end of the row 180s.
Edit: Things are usually rusted up pretty good. A good quality penetrating oil is a must and giving it time to soak in is necessary. PB Blaster at any auto store works fine. Cheater bars and a pipe wrench on the spacers with a good forged boxed end on the nut with a smack from a sledge hammer to get the nut moving....then a cheater bar on the nut...keep the penetrating oil coming.
Same with getting the axle out.....PB Blaster all along the length, axle removed from the implement or on, whichever you prefer, 3" sledge on the end of the axle with nut still on adjusted flush with the end of the axle, hardwood block between sledge and axle to keep from deforming the axle tip and threads.
As you get some spacing, go along the length of the axle with the sledge and give each disc a tap to move it along as the axle comes out.
If you have to, get out your welding equipment and adapt the hangers to fit a new bearing type that may be necessary because of failure of existing bearings. ASC has sealed (and 3 rubber ridges sealed per side) or equipped with Zerks....same seals....have used both types and for limited use, sealed with no zerks works ok.
