HK t-60.....

Go to The Vinyl Engine where you can download the owner's and service manuals for both units. All units are very similar in appearance with slight differences in specs. I have a T60 and T65C, both of which have the floating 3 point suspension. According to the owner's manual from Vinyl Engine, the T45 does not. The floating suspension was the deal maker for me back in the day when I bought my T60. Great isolation from ambient noise. Tap on my dust cover or cabinet and you won't hear it from the speakers.
Not sure if you can adjust the VTA on the T45, you can on the T65C as well as the T55C/T60, even though the procedure isn't mentioned in the T55C/T60 manual. I won't go into the VTA thing here, tweaking can change the sound, depending on your cartridge/system.
If you can make sense of the circuit schematics in the service manuals, you can't miss how much more complex the circuitry is on the T55C/T60 vs the T45. And the T65C is even more complex. For one thing, the filtering and storage on the T45's power supply is practically nonexistent, compared to that of the T55C/T60. And the T65C is even better.
What's all the above mean to you? I dunno. Depends on the rest of your system and what you can hear. On my system however, the T65C was such a noticeable and surprising improvement over the T60, it surprised me, given their outward similarities. For one thing, the speed was truer, and not just by the strobe, you could hear it. The bass was deeper, tighter, fuller and more defined than the T60. The T65C is just a much nicer unit to listen to, period. For me.
I have never personally listened to a T40 or T45, so I can't speak from experience how it would compare to the T60/65C. I don't think it would be bad, just not as good. I think more than just bells and whistles separated the models, there was more going on under the hood too. Once you get the service manuals, you may be able to compare parts. For example, is the main bearing the same part number? Is the platter the same, does it weight as much? Are they the same tonearms, can they accommodate the same weight cartridges? I mention this because I also have an HK720. Everything looks similar, but what a mediocre table.

Well had it serviced at a local shop...speed is dead on...auto-lift operates as it should...replaced belt and upgraded cartridge...if I come across a t-60 in my local area i would jump on it...but for the moment settled on the t45 which i acquired for free...the t60 is a better table...but that doesnt necessarily equate to better sound...one can make up some ground by upgrades, etc...thanks for the reply...

Free is good. Wondering if you had it serviced because of failed capacitor speed issues mentioned in a previous thread or just in for a new belt and cartridge? Keep your eyes open for a T65C. That one actually has a nice "bell and whistle" not on the T60, a "cut" button outside of the dustcover. Press it and the tonearm lifts and the platter stops spinning. Much more convenient than opening the dustcover and raising the cue arm. Tonearm on the T65C can also handle a heavier cartridge, giving you more choices.

Service was somewhat basic...they didnt take it apart...put on new belt and cart with adjustments with no labour costs...so far no speed issues....look out for t65...any other sleeper tables from 80s to look for? Technics linear trackers?

I've read some pretty funny reviews from pissed off former owners of the HK linear tracking tables. Funny and former because after the tonearm auto-lifted and scratched a high end record, it got tossed out the window. I didn't even realize technics made a linear tracker, I thought Harman Kardon/Rabco was the unit to get. Never had any interest in anything Technics after I replaced a direct drive model 3 tables before the T65C. I wasn't wild about that direct drive because it rumbled so much. I know Technics is hugely popular and you can find many repaired and modified on the web. And I'm sure they're better now than whatever model I had way back then.
I stuck with the HK all these years mainly because I had no reason to replace it. Of all the turntables between my friends and I, the HK sounded the best. In fact two of my friends bought T60's after hearing mine. I repaired my T60 recently because it would have cost me more than $2500 to replace it with something similar new.
Another turntable from back in the day I had my eyes on was The AR. There's a lot of them around, and very modifiable. One site specializes in repairing, modifying and selling AR tables. He also works on Thorens and has a chronological history of their production models. AR and Thorens are nice because you can change tonearms, but now you're talking big dollars. Linn Sondek is supposed to be pretty good, in fact, the HK T60 is often called the "poor man's Linn". I saw the underside of one once, and boy did it look like my T60. Tonearms were even designed by the same guy.
That said, you can find a T60 on ebay for $250 or less if you are patient. The T65C is harder to come by, I've only seen 2 in the past year, and I bought one of them for $300. I liked it so much I gave my T60 to my son, keep it in the family type thing.
Read up on the T60, you'll never see a bad review. It's a great value, and keeps holding it's value too. Thorens is good, but you have to get the right one. I wouldn't mind an AR if I could modify it. I almost bought an AR way back then, but it didn't have the auto lift and shutoff. The HK was the only one that did.