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Does anybody know if the Spectra FG97a will work/on a 48 custom, and will it need modification for installation?

No, it will not work. That sender has a resistance of 70 E to 10 Full and would be correct for a 51-6 providing the float arm can be bent to fit the tank. The 48-50 sender mounts differently to the tank and those gauges used a sender with a heater operated bimetal contact with an on/off pulsing type operation and not straight resistance. Some Ford products of the era used the same type senders but the bimetal types are getting to be all but nonexistent.

Having said that, Tinman has done a lot of work on finding a modern straight resistance sender that can substitute in the 48-50 models and has a project blog for his 49 at the PAC site detailing some of his experiments. I do know the sender he used has a different ohm range than 10-70. He just recently finished his car and finally has it on the road. Has driven it to a couple of shows but don't know how many tanks of gas that has involved. From what he has posted and told me via PM it seems he may have found an answer but there is still a question on long term stability due to the gauge getting a constant signal vs on/off pulsing and how the constant signal makes the gauge respond.

I don't know if he is completely thru testing yet or if the ohm range of the sender that was mentioned in the blog might be the final version. The first experiments are in the blog but don't remember what page they start on. You might look thru his blog at the PAC site or send a private message to Tinman_70 for details. He also has a blog on this site but it is not as complete in detailing the sender work as the PAC entries.

The sender he used may not be usable as is on your tank without additional mounting pieces because his car has a different tank. What he used was another brand tank modified to fit the car but at least the sender ohm range would be a start. A modern universal sender in that range could probably be modified to fit the Packard tank or a better version needing less work and with ready made mounting adapters might be available at Classic.https://www.packardclub.org/forum/viewtopic.php?f=15&t=2251

Thanks ever so much! Had not seen Tinman's story until now - quite similar to mine - although my Custom didn't have as much rust. Considering making an access hole for the sender (I know - not correct, nor are my dual master cylinder and seat belts/harnesses) so I can get the car into service again until I resolve sending unit.

I am a firm believer in having an access hole for the sender and think of them as one of those small things Packard neglected to include. Have added them to my 47 and 56. Done neatly with the usual mat or carpet on the trunk floor the hole would not be too noticable. The 22-23 series trunk floors are similar to the 47 in that they have the same small bump up for the sender terminal clearance and could be drilled similarly. Easy enough to do if the tank is already down to work on a sender.

Here is an old thread with photos of my access hole and some showing how another poster did his on a 22-23 series plus a bit of info on the bimetal senders.https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=186125#forumpost186125

On another subject you just touched upon in your post, there have been several inquires on installing dual master cylinders. Do you have any details on components or photos you could share on how yours was done?

From my experience, your best bet is to spend the money and have the original sending unit rebuilt, if possible. The set up I used in my '49 worked for me because I used a '53 Chevy gas tank to replace the rusted original and the GM sender was a bolt-on, won't fit the Packard tank. Also required adding high-watt resisters inline with the gauge to get it to read correctly. Have taken 2 trips, 60 miles and 200 miles and the gauge is reasonably accurate. A rusted out sender and gas tank are common problems for the Series 22 and 23, you'd think someone would make replacements!

I fully agree with Tinman, if your existing unit is repairable, that is by far the easiest way to go. Wolf & Co. has always been excellent for this type of work and I'm assuming they still are.

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Thanks everybody!! I've talked to the folks at Wolf and was impressed with their apparent knowledge, so I sent the old unit to them for evaluation. We'll see... They felt that there was no suitable retrofit for the unusual bimetal system Packard used in this series car. Still plan to put in an access hole though - doubt if it will look as good as Howard's! As to the dual master cylinder, I hate to admit, but I did this so long ago I have no recollection of where I sourced the item (many years and many cars ago - but I still have my beloved Custom). Will try to post a photo when I get the time!

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Hi; If John Wolf is unable to repair your sending unit, please let me know as I sold my 48 custom and have an extra unit that is NOS I believe. I send sent you a PM. Dell