The Ford Motor Co. reported here yesterday that a staggering 88 percent share of its worldwide profits for the third quarter of 1978 had been earned outside North America on a scant 33 percent of sales.

Ford's sales in the three months ending Sept. 3 totalted $9.7 billion, of which $6.5 billion or 67 percent, were made in North America, and $3.2 billion sales or 33 percent were made outside of the United States and Canada.

But it was the profit relationship in the three months that made the most remarkable item: The No. 2 automaker worldwide made $35 million profit in the United States and Canada and $266 million outside those two countries, for a total of $301 million profit in th three months. That meant that Ford made 12 percent of its profit in the United States and Canada and 88 percent outside of those two North American countries.

Henry Ford II, chairman of the board of Ford Motor Co., said in a prepared statement that the company's "worldwide sales, employment, as well as employe compensation and benefits, were at a record level for any third quarter in the company's history."

The company also said:

The U.S. rail strike cost Ford $36 million in sales, or approximately 15,000 units. We expect to recover 11,000 of those lost sales in the fourth quarter," a company spokesman said.

Ford's assets - in cash and marketable securities - fell by more than $2 billion, from $4 billion on June 30 to $1.9 billion on Sept. 30. That was because of the introduction of 1979 model cars, where payment from dealers was not due until Oct. 6, the introduction date, according to a Ford spokesman.

A Ford spokesman, asked to explain the large downward shift in profits in the United States - last year profits in the three months were $128 million, compared to $35 million for the June through September period - said the third quarter was traditionally a low point for auto makers. The reason is that the new models and the expenses for them are absorbed in those three months.

Remarkable in the Ford quarterly report is that fact that the company has just begun to dedicate effort to selling its products worldwide, and that the auto makers in other nations are responding similarly.

What is happening, although it's rarely said, is that the automobile industry worldwide is becoming a "common" market all of its own. And the competition between the among companies and countries is fiercely on the rise.

Texaco announced its third quarter profit decline 14.2 per cent over the similar period a year ago, due primarily to foreign currency translation losses.

The company said yesterday its profit was $212.8 million (69 cents a share) down from last year's $247.9 million (91 cents). Revenues eased to $7.04 billion from $7.07 billion.

Texaco's nine-month profit declined 23.3 per cent to $558.6 million or (2.06) from $728.4 million ($2.68) a year ago, Revenues fell to $20.86 billion from $21.24 billion.

Maurice F. Granville, chairman, said net profits for the third quarter showed improvement over the first and second quarters despite a substantial increase in foreign currency translation losses from the decline of the dollar's value.

Despite the negative effect of a claims settlement worth $9 million with the U.S. Navy, Tenneco Inc. had a 6 percent increase in earnings for their third quarter ended Sept. 30.