Platter Upgrade for VPI HW MK lll to MKlV

I own a VPI HW MK lll with the 1" acrylic & lead platter and would like to upgrade the plater to MKlV. I think all that is available new right now is the 1.5 " all acylic Scout platter w/inverted bearing. Or should I look for an older TNT lead and acylic platter without the inverted beaaring which was the older true upgrade. Could anyone give me some suggestions.
Also, watch your weights and clearances. The heavier platter may require different suspension springs or else your plinth might be tilted. The thicker platter may require a higher dustcover, assuming you have the low-rise dustcover standard for the Mark III. Check to make sure your arm can be raised sufficiently to provide proper VTA.
I have the older TNT acrylic and lead platter,with the original bearing, on my Mark 4, and think it's the way to go. As noted above, you will also need the bearing shaft that goes with this platter, as well as the heavier springs.

I replaced the springs on my Mark 4 with the Sorbothane pucks used in the last production runs of this TT, and they made a distinct improvement. Previously, due to my old flooring, the TT was very susceptible to footfalls (even light ones), but the Sorbothane pucks have essentially eliminated this problem. I also think the bass sounds tighter. Changing over to the pucks requires a minor modification to the TT base, but it's not difficult. You can send me a private E-mail if you want more detail.

I also replaced the small, rubber feet with the aluminum cone feet used on the Scout and Aries series of turntables, and they provided a small but useful incremental improvement.

The Sorbothane pucks and the aluminum cone feet can be purchased from several sources, including directly from VPI. I bought mine from Elusive Disk - here's the link:

With the heavier Mk4/TNT platter, bearings, Sorbothane pucks, and cone feet, you will notice a real improvement in the performance of your HW-19 Mk3.
I myself went the old standard MK-IV Platter with my bought new in '96 JR Table. (Standard JR MDF Plinth w/Sorbothane Pucks)

The Changeout was no effort, as the older MK=IV Bearing Well dropped right in.

It was then as others have said, getting all other paramaters adjusted. The extra weight, which fortunately is evenly distributed across the Plinth did cause a slight drop in Plinth height, and also due to the elimination of four spindle washers that VPI themselves placed, placing one washer upon each Sorbothane Puck.

This was no doubt done by VPI to insure clearance between the Motor Pulley Cover, and Motor Pulley.

Once I installed the Heavier Platter, and removed the Spindle Washers, a clearance problem occurred between Pulley, and Cover, and a slightly thicker rubber washer was then needed in betwen the three standoffs, and cover.

The other issues may be also Dustcover clearance between it, and the Spindle Clamp. I had this problem, and let a good freind fabricate a beautiful solid Billet Aluminum Screw Clamp Puck, and I'm utilizing an older BDR Coaster in combination with it (two piece clamp).

Lastly, when the MK-IV Platter was installed, naturally VTA needed to be raised, and with my own AQ PT-8 Arm, there was a heck of a lot of Tonearm Mounting Shaft showing on the arm, and it looked horrible.

Here again, for a small price, I opted to let my freind machine a .5" thick Aluminum Spacer (Donut) and installed it between my Arm, and Plinth. Since the Original Tonearm Mounting base was still used in this configuration, there was no need to install a means of retaining the Arm with the spacer (Allen Locking Screw)

Other options, yet more costly, to aleveiate-correct this issue, would've been perhaps the Pete Riggle VTAF device, and this would've increased Arm height by I understand .250".
The other feature gained by this device is the ability to play with VTA settings on the fly, an option I don't have with the .5" Spacer, and felt I didn't really need.

Not long ago, I did see VPI still state they had remaining stock of Mk-IV Platters, and cost was listed at $700. I assume this Platter uses, and came with the newer, inverted Bearing.
Hope this helps, Mark
Thanks for taking the time to answer my post. Your answers were very helpful and appreciated.