FINANCIAL MARKETS : Buck Falls Below 84; Stocks, Bonds Commiserate : Wall Street: Central banks’ rescue efforts fail. Weaker March jobs report also takes its toll.

The dollar tumbled to yet another record low against the Japanese yen Friday, crashing through the 84-yen barrier for the first time, as concerted intervention by central banks again failed to revive the plunging currency.

Blue-chip stocks and bonds fell as investors took profits from the week’s rally, prompted by the dollar’s weakness and news of slower job growth in March.

The dollar closed in New York trading at a new post-World War II low of 83.65 yen, down from 85.30 on Thursday, bringing its loss against the yen to 3.1% in the past week. So far this year, the dollar has dropped about 15% against the yen.

The dollar also hit record lows overnight in Asian trading, leading the Bank of Japan to intervene. It managed to pull the dollar higher, but the relief was only temporary.

The dollar came under pressure after the Labor Department said the U.S. unemployment rate edged up to 5.5% in March from 5.4% in February as job creation slowed to a more moderate pace.

Slower economic growth makes it less likely that the Federal Reserve Board will raise interest rates, giving foreign investors less incentive to put money in dollar-denominated assets.

The dollar remained mostly steady against the mark as dealers took profits on the Germany currency, which began to retreat against European counterparts. The dollar finished at 1.3760 marks, down from 1.3762.

On Wall Street, stocks ended mixed after a fitful session as the twin threats of a slowing economy and inflation sent the blue chips lower.

The Dow industrial average slid 36 points but recovered most of that loss, closing down 12.79 at 4,192.62.

Broader market indexes were mixed. The New York Stock Exchange’s composite index fell 0.05 point to 273.73. But the Standard & Poor’s 500-stock index rose 0.34 point to 506.42, topping its record high of 506.08 set Thursday.

The Nasdaq composite index climbed 0.89 point to 814.69. The American Stock Exchange’s market value index rose 0.48 point to 469.35.

Declining issues edged out advancers by about 11 to 9 on the NYSE. Big Board volume was a hefty 314.76 million shares, compared to 320.47 million Thursday.

The bond market eroded further, with the benchmark 30-year Treasury bond yield rising to 7.39% from Wednesday’s 7.34%. Its price, which moves in the opposite direction, fell 9/16.

Bond investors usually like weak economic news because it generally means inflation is waning. But the dollar’s weakness helped reverse bonds’ gains and pressured the Dow lower.

Also pulling the market down were oil stocks, which fell after Salomon Bros. downgraded several issues. Salomon warned that the price of oil could fall if the United Nations approves a pending proposal to allow Iraq to increase its oil sales.

Among Friday’s highlights:

* Among the issues downgraded by Salomon were Chevron, which fell 3/4 to 45 1/2; Texaco, which finished unchanged at 65, and Mobil, which fell 5/8 to 89 1/2. The brokerage kept its rating on Exxon, which rose 1/8 to 66 1/8; Royal Dutch Petroleum, which rose 1/4 to 121; British Petroleum, up 1 1/2 to 83 3/4, and Shell Transportation & Trading, an owner of Royal Dutch Shell, which slid 1 3/8 to 69 1/2.

* Banking stocks were mixed after posting sharp gains Thursday. Chase Manhattan rallied another 7/8 to 42 1/2 after rising sharply Thursday on news that investor Michael Price had taken a large stake in the company’s stock. Price is known for buying cheap stocks and goading management of those companies into making changes to enhance share value. But Chemical fell 3/8 to 40 5/8, and Citicorp eased 1/8 to 45 1/8.

* DuPont fell 2 3/8 to 62 3/8 on concern over a planned reissue of a portion of shares that were repurchased from the Canadian distiller Seagram Co. Seagram fell 1 3/8 to 26 1/2 on concern about its pending acquisition of 80% of Matsushita Electric Industrial’s entertainment unit, MCA.

* Among technology stocks rebounding from recent profit taking, Micron Technology rose 1 3/8 to 76 1/4 and Intel was up 1 5/8 to 87 1/8.

Overseas markets were mixed. In Mexico City, the Bolsa index jumped 37.38 points, or nearly 2%, to close at 1,952.16.

Tokyo’s stock market showed resilience despite the rising yen. The 225-share Nikkei average closed down 96.37 points at 15,719.50. In London, the FTSE-100 average closed 10 points higher at 3,210.9; Frankfurt’s 30-share DAX average gained 2.61 points to 1,981.88.