Hi Luciano, This reply is general in nature as there may be others interested. I have two late generation HP 3455As and three HP 3456As that are in excellent physical condition, always used in a lab environment and stored in the lab storeroom for the last decade, never in the hands of a reseller. They all currently work and measure surprisingly accurate even after being stored. I have been procrastinating about reconditioning all of them electrically and calibrating them for resale. Some of the hesitation on doing a complete restore job (all new electrolytic, contact cleaning, line filter, fan, etc...) like I have done on several 3458As is the relative low selling price even after a restore job. Either model will tromp the HP 34401A other than calibration effort/time and the 3455A is known to be outstanding in AC measurements (not a TC though). When still in use, they were on 24/7 for many years and all have EXCELLENT stabilized voltage references and will return to that stability after a few months of operation. I have already started a burn-in on all units prior to calibration. They have been on for 3-weeks now, all working. The considered rebuild job is primarily for reassurance the instrument will perform well for many more years. My hesitancy to rebuild also considers that maybe the buyer would rather do it himself after buying the unit at a lower price. I'm retired now and my time is a labor of love for these instruments and I can put the time into them that I know can never be recovered. The parts, on the other hand, I do need to recover and that will add about $120 US per unit. The going price on eBay for either model seems to be $150 - $300 for working units. I would like to get the higher end of that for mine working and calibrated but no rebuild. Just something for you to consider. Will answer all questions. Regards, Don Johnson Midwest, USA