This shaft is still available to order from Titleist - Diamana Ltd M+ Red 60, the Ltd is one model newer. Titleist only offers 40-50-60 shafts, no 70. Looks like you have a 60 already. Mitsubishi lists a 70 in their M+ Plus series in R-S-X in their catalog. Custom fitters like Club Champion, The GolfWorks. or other retailers may be able to obtain the shaft and add a third party copy of a Sure-Fit adapter (or pull a factory one from a spare shaft from you).

It's not common to use the same weight shaft in a driver. Most will use a 60 g in a fairway and a 50 g in a driver. Especially with higher launching shafts. If the 60 is too whippy, maybe increasing the flex stiffness will help. The other option is to see if another newer shaft will work better. A Titleist Thursday can help you decide. The Diamana Red/Blue shafts have been replaced in the Titleist stock models by the Kuro Kage Tini & Silver and the Tensai Blue (and Orange) models.